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

props westonruter.
fixes #30225.
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Twenty Fifteen: Make sure that the edit link will always be right of it's icon.

Props iamtakashi, fixes #30171.



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Twenty Fifteen: Use new core navigation tags.

Props obenland, iamtakashi, fixes #30189



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Twenty Fifteen: kern everything -- it reads better.

Props afercia, fixes #30195.



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Twenty Fifteen: escaping for the HTML5 shiv call.

Props philiparthurmoore, fixes #30212



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Customizer: Bind `input` and `propertychange` events for range input types.

props voldemortensen, westonruter.
fixes #30223.
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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.



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Twenty Fifteen: check if user-selected custom colors are the same as default so we're not duplicating styles.

Props iamtakashi, fixes #30234


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Twenty Fifteen: correct image alignment for RTL.

Props iamtakashi, fixes #30239.



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Introduce some new template functions for archive titles and descriptions:

 * `get_the_archive_title()` and `the_archive_title()` for returning/displaying the title of the current term, date, post type, post format, or author archive.
 * `get_the_archive_description()` and `the_archive_description()` for returning/displaying the description associated with the current term archive.

Fixes #21995
Props obenland, DrewAPicture

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