On attachment pages for audio and video, display players. Currently, only a link is displayed. Add minimal CSS rules for compatibility with 2011, 2012, and 2013 themes.

In `prepend_attachment`, add logic to support attachment types that are not `image`.

In `get_post_class()`, don't add the `has-post-thumbnail` class for attachment pages.

Fixes #27243.


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git-svn-id: http://core.svn.wordpress.org/trunk@27465 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: remove `post_class` filter for `has-post-thumbnail` now that it's added in core for every theme. See #18804.
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git-svn-id: http://core.svn.wordpress.org/trunk@27466 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: revert r27623 `post_class` filter removal since it will visually break pre-WP 3.9 installs. See #18804.
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git-svn-id: http://core.svn.wordpress.org/trunk@27467 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Only enqueue the image editor in the media modal in the admin.

props gcorne.
see #21811.

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Remove "Show" prefix from filter dropdowns, see #26743.
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git-svn-id: http://core.svn.wordpress.org/trunk@27469 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: load Masonry after window load event to give more time for widget content to load before drawing the layout. Closes #27051.
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