Twenty Fifteen: Simplify the header, sidebar, background controls and make customization faster for users to do. This has the added benefit of fixing our bug where hidden header text wasn't being updated on color scheme switch. Nice.

Props celloexpressions, iamtakashi, fixes #30164 and #29980.

Built from https://develop.svn.wordpress.org/trunk@30230


git-svn-id: http://core.svn.wordpress.org/trunk@30230 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: accessible alt text for post thumbnail links.

Props joedolson, fixes #30076.


Built from https://develop.svn.wordpress.org/trunk@30231


git-svn-id: http://core.svn.wordpress.org/trunk@30231 1a063a9b-81f0-0310-95a4-ce76da25c4cd