Commit Graph

1002 Commits

Author SHA1 Message Date
Pascal Birchler 8fe586ad57 Toolbar: Add a 'View Posts' link to the toolbar when on the post listing screen.
This adds a new link to visit the post type archive if the post type supports it. Also introduces a new `view_items` label to `get_post_type_labels()`.

Props paulwilde, akibjorklund, swissspidy.
Fixes #34113.
Built from https://develop.svn.wordpress.org/trunk@38634


git-svn-id: http://core.svn.wordpress.org/trunk@38577 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-09-20 20:02:28 +00:00
John Blackbourn e0a0be9579 Media: Add a `$wp_error` parameter to `wp_insert_attachment()` to give it parity with `wp_insert_post()`.
Fixes #37813
Props grapplerulrich, mrahmadawais

Built from https://develop.svn.wordpress.org/trunk@38408


git-svn-id: http://core.svn.wordpress.org/trunk@38349 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-08-27 17:25:29 +00:00
Sergey Biryukov 64dac53d70 I18N: Use a consistent context for "Add New" submenu strings in admin bar (Toolbar).
Props ramiy.
Fixes #37780.
Built from https://develop.svn.wordpress.org/trunk@38326


git-svn-id: http://core.svn.wordpress.org/trunk@38267 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-08-23 01:42:32 +00:00
Dominik Schilling 75d4429926 Post Thumbnails: Restore thumbnail support for media files.
* Allow to add/remove a featured image to `attachment:audio` and `attachment:video` post types, see [27657].
* Change conditionals to check for theme OR post type support.
* Add tests for #12922.

Broken in [37658].

Props flixos90, joemcgill, DrewAPicture, wonderboymusic.
See #12922.
Fixes #37658.
Built from https://develop.svn.wordpress.org/trunk@38263


git-svn-id: http://core.svn.wordpress.org/trunk@38204 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-08-15 19:16:31 +00:00
John Blackbourn ab052361a3 Docs: Correct and clarify various `@since` docs.
Fixes #37562

Built from https://develop.svn.wordpress.org/trunk@38201


git-svn-id: http://core.svn.wordpress.org/trunk@38142 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-08-04 22:54:31 +00:00
Sergey Biryukov db9ec644f5 Permalinks: In `get_page_uri()`, don't prepend a parent page slug if it's empty.
Props inderpreet99, SergeyBiryukov.
Fixes #36174.
Built from https://develop.svn.wordpress.org/trunk@38145


git-svn-id: http://core.svn.wordpress.org/trunk@38086 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-23 10:05:49 +00:00
Drew Jaynes e6267dcf19 Docs: Fix formatting, tense, verb conjugation, and other syntax for wp-includes/* elements introduced or changed in 4.6.
Part 2/2.

Fixes #37318.

Built from https://develop.svn.wordpress.org/trunk@38125


git-svn-id: http://core.svn.wordpress.org/trunk@38066 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-20 19:33:30 +00:00
Joe McGill 3dbba0fff3 Post Thumbnails: Only update featured images when saving a post.
Previously, changing the post thumbnail of a published post in the edit screen
would immediately apply the change, rather than waiting for the post to be
saved before applying the update. This could lead to someone unintentionally
editing the post thumbnail on a published post, and made it impossible to
preview changes to post thumbnails on published posts before saving the change.

This introduces a new Ajax handler, `wp_ajax_get_post_thumbnail_html()` to
retrieve the HTML for the post thumbnail meta box without updating the post
meta value for `_thumbnail_id`. It also allows post thumbnail changes to be
previewed by passing the `_thumbnail_id` as a query variable to the preview
screen and adding a new filter, `_wp_preview_post_thumbnail_filter()`, which
gets applied to `get_post_metadata` during the post preview process.

Props flixos90.
Fixes #12922.
Built from https://develop.svn.wordpress.org/trunk@38118


git-svn-id: http://core.svn.wordpress.org/trunk@38059 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-20 16:24:28 +00:00
Sergey Biryukov 866bd39813 I18N: Combine two duplicate "Invalid post type" strings.
Props @ramiy.
See #18218.
Built from https://develop.svn.wordpress.org/trunk@38076


git-svn-id: http://core.svn.wordpress.org/trunk@38017 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-17 16:05:31 +00:00
Sergey Biryukov f5aab6e25d Docs: Correct `$post` parameter name and description for `wp_attachment_is()` and `wp_attachment_is_image()`.
Props flixos90.
Fixes #37377.
Built from https://develop.svn.wordpress.org/trunk@38068


git-svn-id: http://core.svn.wordpress.org/trunk@38009 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-16 13:05:29 +00:00
Drew Jaynes 60de6917fb Docs: Add and clarify changelog entries for elements that can now accept, use, or return `WP_Post_Type` objects.
Also adds a missing initial `@since` version for `wp_xmlrpc_server::_prepare_post_type()`.

See [37890]. See #36217.

Built from https://develop.svn.wordpress.org/trunk@38051


git-svn-id: http://core.svn.wordpress.org/trunk@37992 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-13 15:24:28 +00:00
Sergey Biryukov 139387b7e5 Docs: Use 3-digit, x.x.x-style semantic versioning for `_doing_it_wrong()`, `_deprecated_function()`, `_deprecated_argument()`, and `_deprecated_file()` throughout core.
Props metodiew.
Fixes #36495.
Built from https://develop.svn.wordpress.org/trunk@37985


git-svn-id: http://core.svn.wordpress.org/trunk@37926 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-07-06 12:40:29 +00:00
Joe McGill 170d22a22c Post Thumbnails: Add helper functions for attachment captions.
This adds three new functions for getting/displaying attachment captions:

* `wp_get_attachment_caption` - Retrieves a caption for a specific attachment.
* `get_the_post_thumbnail_caption()` - Returns the post thumbnail caption.
* `the_post_thumbnail_caption()` - Displays the post thumbnail caption.

These are helpful for displaying a caption associated with an image directly
in a template, rather than using the caption shortcode.

This also introduces two new filters:

* `wp_get_attachment_caption` - Filters the value of `wp_get_attachment_caption()`.
* `the_post_thumbnail_caption` - Filters the display of the post thumbnail caption.

`the_post_thumbnail_caption()` is automatically filtered by `wptexturize()`,
`convert_smilies()`, and `convert_chars()` in `wp-includes/default-filters.php`.

Props flixos90, joemcgill.
Fixes #12235.
Built from https://develop.svn.wordpress.org/trunk@37915


git-svn-id: http://core.svn.wordpress.org/trunk@37856 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-29 17:28:28 +00:00
Dominik Schilling 60dc856d64 Posts: Introduce `WP_Post_Type` and use it in `register_post_type()` and `unregister_post_type()`.
This changes the global `$wp_post_types` to an array of `WP_Post_Type` objects. `WP_Post_Type` includes methods to handle post type supports, rewrite rules, meta boxes, hooks, and taxonomies.
Each post type argument becomes a property of `WP_Post_Type`.

Props swissspidy, flixos90.
Fixes #36217.
Built from https://develop.svn.wordpress.org/trunk@37890


git-svn-id: http://core.svn.wordpress.org/trunk@37831 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 16:41:35 +00:00
Drew Jaynes 0ef938e9da Docs: Improve formatting and syntax of the defaullt label docs in the DocBlock for `get_post_type_labels()`.
See #32246.

Built from https://develop.svn.wordpress.org/trunk@37886


git-svn-id: http://core.svn.wordpress.org/trunk@37827 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 07:18:27 +00:00
Drew Jaynes 538eb01e6f Docs: Add a more complete `$labels` parameter description to the DocBlock for `register_post_type()`.
Directly references `get_post_type_labels()` for the full list of supported labels.

See #32246.

Built from https://develop.svn.wordpress.org/trunk@37885


git-svn-id: http://core.svn.wordpress.org/trunk@37826 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 06:42:28 +00:00
Drew Jaynes 112992ba80 Docs: Improve the `$post_type` parameter description in the DocBlock for `register_post_type()`.
See #32246.

Built from https://develop.svn.wordpress.org/trunk@37884


git-svn-id: http://core.svn.wordpress.org/trunk@37825 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 06:37:28 +00:00
Drew Jaynes d4ae5b76ee Docs: Add more complete documentation for the `$supports` argument in `register_post_type()`.
See #32246.

Built from https://develop.svn.wordpress.org/trunk@37883


git-svn-id: http://core.svn.wordpress.org/trunk@37824 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 06:32:27 +00:00
Drew Jaynes 9ef5fb0a17 Docs: Improve the usefulness, accuracy, and syntax of the `register_post_type()` DocBlock summary and description.
See #32246.

Built from https://develop.svn.wordpress.org/trunk@37882


git-svn-id: http://core.svn.wordpress.org/trunk@37823 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-28 06:27:32 +00:00
Jeremy Felt 6f3f00ea97 Multisite: Change `WP_Network` `id` property to an integer.
For consistency and developer sanity.

Props flixos90.
Fixes #37050.

Built from https://develop.svn.wordpress.org/trunk@37870


git-svn-id: http://core.svn.wordpress.org/trunk@37811 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-26 14:26:29 +00:00
Drew Jaynes 1e48cc8a05 Docs: Improve the return description for `wp_get_post_categories()` to include more information about possible return values.
Props jeherve for the initial patch.
Fixes #37002.

Built from https://develop.svn.wordpress.org/trunk@37686


git-svn-id: http://core.svn.wordpress.org/trunk@37652 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-06-11 17:08:28 +00:00
Drew Jaynes 9193013158 Docs: Apply inline `@see` tags to hooks referenced in DocBlocks in a variety of wp-includes/* files.
Applying these specially-crafted `@see` tags allows the Code Reference parser to recognize and link these elements as actions and filters.

Fixes #36921.

Built from https://develop.svn.wordpress.org/trunk@37544


git-svn-id: http://core.svn.wordpress.org/trunk@37512 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-23 19:02:28 +00:00
Drew Jaynes dcadd35728 Docs: Standardize filter docs in wp-includes/post.php to use third-person singular verbs per the inline documentation standards for PHP.
See #36913.

Built from https://develop.svn.wordpress.org/trunk@37504


git-svn-id: http://core.svn.wordpress.org/trunk@37472 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-22 18:31:28 +00:00
Drew Jaynes f52a8cb1fa Docs: Remove/replace invalid inline `@link` tags in DocBlocks in wp-includes/*.
Fixes #36910.

Built from https://develop.svn.wordpress.org/trunk@37487


git-svn-id: http://core.svn.wordpress.org/trunk@37455 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-22 17:39:28 +00:00
Boone Gorges 4428a031a3 In `get_page_by_path()`, values fetched from cache should obey `$output` param.
Introduced in [37479].

Props spacedmonkey.
Fixes #36711.
Built from https://develop.svn.wordpress.org/trunk@37481


git-svn-id: http://core.svn.wordpress.org/trunk@37449 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-22 16:19:29 +00:00
Boone Gorges 98050e404d Cache queries in `get_page_by_path()`.
Props spacedmonkey.
Fixes #36711.
Built from https://develop.svn.wordpress.org/trunk@37479


git-svn-id: http://core.svn.wordpress.org/trunk@37447 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-21 17:27:29 +00:00
Sergey Biryukov ff37a3b730 Docs: Fix typo in a comment in `check_and_publish_future_post()`.
See #32246.
Built from https://develop.svn.wordpress.org/trunk@37403


git-svn-id: http://core.svn.wordpress.org/trunk@37369 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-08 12:46:29 +00:00
Eric Lewis aba14233d9 Posts: Allow `get_page_uri()` to be called without a $page argument.
`get_page_uri()` can now be called without an argument, which will return the page URI for the current post in the loop.

Props pollett.
Fixes #26284.

Built from https://develop.svn.wordpress.org/trunk@37345


git-svn-id: http://core.svn.wordpress.org/trunk@37311 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-02 18:29:29 +00:00
Drew Jaynes fe3b007fdd Docs: Remove inline `@see` tags from function, class, and method references in inline docs.
Known functions, classes, and methods are now auto-linked in Code Reference pages following #meta1483.

Note: Hook references are still linked via inline `@see` tags due to the unlikelihood of reliably matching for known hooks based on a RegEx pattern.

See #32246.

Built from https://develop.svn.wordpress.org/trunk@37342


git-svn-id: http://core.svn.wordpress.org/trunk@37308 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-02 04:00:28 +00:00
Sergey Biryukov 49a47bb255 Docs: Document the `@return` value of `wp_add_trashed_suffix_to_post_name_for_post()`.
Props Shelob9.
Fixes #36728.
Built from https://develop.svn.wordpress.org/trunk@37334


git-svn-id: http://core.svn.wordpress.org/trunk@37300 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-05-01 10:16:29 +00:00
Boone Gorges 742e0005c6 Add parameter documentation for 'post_category' to `wp_insert_post()`.
Props Latz.
Fixes #36601.
Built from https://develop.svn.wordpress.org/trunk@37255


git-svn-id: http://core.svn.wordpress.org/trunk@37221 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-04-20 13:54:30 +00:00
Boone Gorges 374a489166 In `sanitize_post_field()`, only run 'attribute' or 'js' escaping when necessary.
Props tfrommen.
Fixes #34900.
Built from https://develop.svn.wordpress.org/trunk@37220


git-svn-id: http://core.svn.wordpress.org/trunk@37186 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-04-16 14:51:28 +00:00
Boone Gorges cfab9716e3 Use `__trashed` suffix rather than `-%trashed%` for trashed post slugs.
Percent signs are reserved characters in URIs. As such, it was impossible for
plugins to route requests to trashed posts, as happens in bbPress. The new
`__trashed` suffix should be sufficiently unique.

Also adds a test that demonstrates that the `__trashed` suffix can be
appended to slugs that contain the suffix somewhere other than the end of
the string.

Props netweb, ericlewis.
Fixes #11863.
Built from https://develop.svn.wordpress.org/trunk@37165


git-svn-id: http://core.svn.wordpress.org/trunk@37132 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-04-07 19:22:28 +00:00
Drew Jaynes f9919442e2 Docs: Improve the DocBlock summary for `wp_queue_posts_for_term_meta_lazyload()`, introduced in [36566].
See #35816. See #35986.

Built from https://develop.svn.wordpress.org/trunk@36945


git-svn-id: http://core.svn.wordpress.org/trunk@36913 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-03-10 18:29:26 +00:00
Drew Jaynes 49803ffabe Docs: Improve the accuracy of the return description for `unregister_post_type()`, introduced in [36316].
See #14761. See #35986.

Built from https://develop.svn.wordpress.org/trunk@36944


git-svn-id: http://core.svn.wordpress.org/trunk@36912 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-03-10 18:25:25 +00:00
Boone Gorges e032560e6b Correct `@return` annotation for `wp_set_object_terms()` and related functions.
The return value is an array of term taxonomy IDs, not term IDs.

Fixes #36182.
Built from https://develop.svn.wordpress.org/trunk@36896


git-svn-id: http://core.svn.wordpress.org/trunk@36864 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-03-09 16:17:28 +00:00
Drew Jaynes 2846e3aaef Docs: Use the correct variable name for the `$post_ID` parameter in the DocBlock for `wp_add_trashed_suffix_to_post_name_for_trashed_posts()`.
See #11863. See #32246.

Built from https://develop.svn.wordpress.org/trunk@36727


git-svn-id: http://core.svn.wordpress.org/trunk@36694 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-26 09:25:26 +00:00
Drew Jaynes 1b9a705394 Docs: Standardize summaries for two new internal functions used to handle suffixing trashed posts.
Also adds a notation of private access to each.

See #11863. See #32246.

Built from https://develop.svn.wordpress.org/trunk@36726


git-svn-id: http://core.svn.wordpress.org/trunk@36693 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-26 09:23:25 +00:00
Dominik Schilling e5ea82d81a Spelling: Standardize on "front end"/"back end" (noun) and "front-end"/"back-end" (adjective).
Props obrienlabs, thewanderingbrit.
Fixes #34887.
Built from https://develop.svn.wordpress.org/trunk@36709


git-svn-id: http://core.svn.wordpress.org/trunk@36676 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-25 12:53:27 +00:00
Drew Jaynes 4c3c2b315f Posts: Rename the `$args` parameter in `get_post_types_by_support()` to `$feature` for better self-documentation.
See #34010. See #32246.

Built from https://develop.svn.wordpress.org/trunk@36704


git-svn-id: http://core.svn.wordpress.org/trunk@36671 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-25 04:55:25 +00:00
Pascal Birchler 8725644d40 Posts: Introduce `get_post_types_by_support()`.
Similar to `get_post_types()`, this new function returns a list of post type names that support a specific feature.

Props wpsmith, barryceelen, swissspidy.
Fixes #34010.
Built from https://develop.svn.wordpress.org/trunk@36652


git-svn-id: http://core.svn.wordpress.org/trunk@36619 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-23 22:50:26 +00:00
Eric Lewis 04da8bb63a Posts: Non-trashed posts should take slug priority over trashed posts.
When determining a unique post slug, trashed posts are taken into account. Previously, new posts would add suffixes to their slugs (e.g. `about-2`) when a post in the trash had the desired slug (e.g. `about`). 

To avoid this behavior, when a post is trashed its slug (i.e. `post_name`) is now suffixed with `-%trashed%`. The post's pre-trash slug is stored as post meta, and if the post is restored from trash, its desired slug is reapplied. 

For existing trashed posts which don't have the `-%trashed%` suffix, the suffix is added when a post with its desired slug is created.

Props ocean90, boonebgorges, ryan, SergeyBiryukov, coffee2code, helen, williamsba1.
See #11863.

Built from https://develop.svn.wordpress.org/trunk@36607


git-svn-id: http://core.svn.wordpress.org/trunk@36574 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-21 21:45:28 +00:00
Andrew Ozz 2d94e025a2 Replace `wp_upload_dir()` with the new `wp_get_upload_dir()` in all cases where a file is not being uploaded. Deprecate `_wp_upload_dir_baseurl()`, and replace it with `wp_get_upload_dir()`.
See #34359.
Built from https://develop.svn.wordpress.org/trunk@36569


git-svn-id: http://core.svn.wordpress.org/trunk@36536 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-18 00:24:27 +00:00
Boone Gorges 571e14f897 More performance improvements to metadata lazyloading.
Comment and term meta lazyloading for `WP_Query` loops, introduced in 4.4,
depended on filter callback methods belonging to `WP_Query` objects. This meant
storing `WP_Query` objects in the `$wp_filter` global (via `add_filter()`),
requiring that PHP retain the objects in memory, even when the local variables
would typically be expunged during normal garbage collection. In cases where a
large number of `WP_Query` objects were instantiated on a single pageload,
and/or where the contents of the `WP_Query` objects were quite large, serious
performance issues could result.

We skirt this problem by moving metadata lazyloading out of `WP_Query`. The
new `WP_Metadata_Lazyloader` class acts as a lazyload queue. Query instances
register items whose metadata should be lazyloaded - such as post terms, or
comments - and a `WP_Metadata_Lazyloader` method will intercept comment and
term meta requests to perform the cache priming. Since `WP_Metadata_Lazyloader`
instances are far smaller than `WP_Query` (containing only object IDs), and
clean up after themselves far better than the previous `WP_Query` methods (bp
only running their callbacks a single time for a given set of queued objects),
the resource use is decreased dramatically.

See [36525] for an earlier step in this direction.

Props lpawlik, stevegrunwell, boonebgorges.
Fixes #35816.
Built from https://develop.svn.wordpress.org/trunk@36566


git-svn-id: http://core.svn.wordpress.org/trunk@36533 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-17 22:58:26 +00:00
Drew Jaynes c55f447ad4 Docs: Revert unintended changes in wp-includes/post.php, mistakenly included in [36497].
See #34988. See #33701. 

Built from https://develop.svn.wordpress.org/trunk@36498


git-svn-id: http://core.svn.wordpress.org/trunk@36465 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-07 02:46:25 +00:00
Drew Jaynes 3785385ea2 Docs: Add a missing version to the file header for wp-admin/term.php, introduced in [36308].
See #34988. See #33701.

Built from https://develop.svn.wordpress.org/trunk@36497


git-svn-id: http://core.svn.wordpress.org/trunk@36464 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-07 02:43:26 +00:00
Boone Gorges 8db393ada6 Make the `$post` param optional in `get_post_field()`.
When `$post` is `null`, the current post object will be returned.

Props sebastian.pisula.
Fixes #35683.
Built from https://develop.svn.wordpress.org/trunk@36481


git-svn-id: http://core.svn.wordpress.org/trunk@36448 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-02-05 18:58:25 +00:00
Boone Gorges de9d742b9a Allow `is_post_type_viewable()` to accept a post type name.
Previously, it accepted only a post type object.

Props spacedmonkey.
Fixes #35609.
Built from https://develop.svn.wordpress.org/trunk@36402


git-svn-id: http://core.svn.wordpress.org/trunk@36369 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-01-26 02:37:26 +00:00
Pascal Birchler 68f12521c8 Post Types: Introduce `unregister_post_type()`.
This new function can be used to completely unregister non built-in post types.

Fixes #14761.
Built from https://develop.svn.wordpress.org/trunk@36316


git-svn-id: http://core.svn.wordpress.org/trunk@36283 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-01-15 12:20:27 +00:00
Pascal Birchler b0b13aff2f Embeds: Allow embedding static front pages and pages having a child page with an `embed` slug.
This makes `embed` a special slug that can't be used for new pages/posts. When `https://example.com/foo/embed/` is an existing page, embeds fall back to `https://example.com/foo/?embed=true`.
Adds unit tests.

Fixes #34971.
Built from https://develop.svn.wordpress.org/trunk@36307


git-svn-id: http://core.svn.wordpress.org/trunk@36274 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2016-01-15 07:56:26 +00:00