Modals: darken all overlays, update all box-shadows and headings, correct thickbox styling, make the link modal narrower and bring back the animation (css transition). Props avryl, see #26952
Built from https://develop.svn.wordpress.org/trunk@27532


git-svn-id: http://core.svn.wordpress.org/trunk@27375 1a063a9b-81f0-0310-95a4-ce76da25c4cd