Customizer: Add stable sorting for panels, sections and controls in JS. Improve sorting in PHP.

props westonruter.
fixes #30225.
Built from https://develop.svn.wordpress.org/trunk@30214


git-svn-id: http://core.svn.wordpress.org/trunk@30214 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: Make sure that the edit link will always be right of it's icon.

Props iamtakashi, fixes #30171.



Built from https://develop.svn.wordpress.org/trunk@30215


git-svn-id: http://core.svn.wordpress.org/trunk@30215 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: Use new core navigation tags.

Props obenland, iamtakashi, fixes #30189



Built from https://develop.svn.wordpress.org/trunk@30216


git-svn-id: http://core.svn.wordpress.org/trunk@30216 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: kern everything -- it reads better.

Props afercia, fixes #30195.



Built from https://develop.svn.wordpress.org/trunk@30217


git-svn-id: http://core.svn.wordpress.org/trunk@30217 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: escaping for the HTML5 shiv call.

Props philiparthurmoore, fixes #30212



Built from https://develop.svn.wordpress.org/trunk@30218


git-svn-id: http://core.svn.wordpress.org/trunk@30218 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer: Bind `input` and `propertychange` events for range input types.

props voldemortensen, westonruter.
fixes #30223.
Built from https://develop.svn.wordpress.org/trunk@30219


git-svn-id: http://core.svn.wordpress.org/trunk@30219 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: Remove a gap between content and footer when the sidebar is longer than the content.

Props iamtakashi, fixes #30228.



Built from https://develop.svn.wordpress.org/trunk@30220


git-svn-id: http://core.svn.wordpress.org/trunk@30220 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: check if user-selected custom colors are the same as default so we're not duplicating styles.

Props iamtakashi, fixes #30234


Built from https://develop.svn.wordpress.org/trunk@30221


git-svn-id: http://core.svn.wordpress.org/trunk@30221 1a063a9b-81f0-0310-95a4-ce76da25c4cd