Move _show_post_preview() back next to _set_preview(). see #23539.

git-svn-id: http://core.svn.wordpress.org/trunk@23866 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Make sure the autosave post exists before getting its meta. props kovshenin. fixes #23539.

git-svn-id: http://core.svn.wordpress.org/trunk@23867 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Fix incorrect script handle and a notice. props ocean90. fixes #23896.

git-svn-id: http://core.svn.wordpress.org/trunk@23868 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge remote-tracking branch 'upstream/master'
Make a copy of post content to avoid changing it in get_the_image(). Remove unnecessary assignment from get_the_media(). props wonderboymusic for initial patch. fixes #23888.

git-svn-id: http://core.svn.wordpress.org/trunk@23869 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Fix some Insert-into-Post for Audio/Video bugs.

props wonderboymusic. see #23831.

git-svn-id: http://core.svn.wordpress.org/trunk@23870 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add "Customize" as first item under Appearance menu.

fixes #21413. props ryanhellyer, obenland, DrewAPicture

git-svn-id: http://core.svn.wordpress.org/trunk@23871 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge remote-tracking branch 'upstream/master'