Allow `int` to be passed in lieu of `array`, add `append` arg to `wp_set_post_categories()`. Adds more extensive unit tests for `wp_set_post_categories()`.

Props ptahdunbar for initial patch.
Fixes #16550.



git-svn-id: http://develop.svn.wordpress.org/trunk@25234 602fd350-edb4-49c9-b593-d223f7449a82
add_theme_support( 'html5' ) now defaults to comment-list, comment-form, and search-form.

This was the implicit case in 3.6.0, modified in [25193].

see #24932.


git-svn-id: http://develop.svn.wordpress.org/trunk@25235 602fd350-edb4-49c9-b593-d223f7449a82
Clarify a database upgrade string, for 3.7.

props SergeyBiryukov.
fixes #24845.


git-svn-id: http://develop.svn.wordpress.org/trunk@25237 602fd350-edb4-49c9-b593-d223f7449a82
Convert `category__and` to `category__in` (less expensive) and unset it when only one category is passed. Adds unit tests.

Fixes #24245.




git-svn-id: http://develop.svn.wordpress.org/trunk@25238 602fd350-edb4-49c9-b593-d223f7449a82