Splits wp-includes/embed-template.php, introduced in 4.4, into five new templates that can be individually overridden by themes:
* embed.php
* embed-404.php
* embed-content.php
* header-embed.php
* footer-embed.php
Also introduces a new template tag for outputting the site title, `the_embed_site_title()`.
The five new templates live in theme-compat, allowing for graceful fallbacks should themes prefer not to override any or all of them.
Props swissspidy, imath, ocean90, DrewAPicture.
See #34561.
git-svn-id: https://develop.svn.wordpress.org/trunk@36693 602fd350-edb4-49c9-b593-d223f7449a82
