Smarter structured post format caching.

fixes #24002. props kovshenin, wonderboymusic.

git-svn-id: http://core.svn.wordpress.org/trunk@24091 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Screen option for Post Format UI.

props nacin. see #23930.

git-svn-id: http://core.svn.wordpress.org/trunk@24092 1a063a9b-81f0-0310-95a4-ce76da25c4cd