Adds `wp.shortcode`, a set of methods used for parsing shortcodes out of content. Also adds a default set of shortcode properties to `wp.mce.view`.
fixes#21996, see #21812, #21813, #21815.
git-svn-id: http://core.svn.wordpress.org/trunk@22004 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Daryl Koopersmith