Remove the private delegation from the following classes and function:
* `WP_List_Table`
* `WP_Application_Passwords_List_Table`
* `WP_Comments_List_Table`
* `WP_Links_List_Table`
* `WP_Media_List_Table`
* `WP_MS_Sites_List_Table`
* `WP_MS_Themes_List_Table`
* `WP_MS_Users_List_Table`
* `WP_Plugin_Install_List_Table`
* `WP_Plugins_List_Table`
* `WP_Post_Comments_List_Table`
* `WP_Posts_List_Table`
* `WP_Terms_List_Table`
* `WP_Theme_Install_List_Table`
* `WP_Themes_List_Table`
* `WP_Users_List_Table`
* `_get_list_table()`
This change is to reflect the reality that list tables are very, very, very widely used by extenders and backward compatibility therefore needs to be maintained.
Introduces the filter `wp_list_table_class_name` within `_get_list_table()` to allow extenders to modify the list table returned for custom screens.
Props audrasjb, birgire, costdev, desrosj, faison, johnbillion, jrbeilke, kurtpayne, milana_cap, miqrogroove, nacin, peterwilsoncc, scribu, sergeybiryukov, sirzooro, westonruter, wonderboymusic.
Fixes#18449.
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git-svn-id: http://core.svn.wordpress.org/trunk@53937 1a063a9b-81f0-0310-95a4-ce76da25c4cd