Use a nested meta query when querying by role in `WP_User_Query`.

If a user query includes a meta query together with a role argument,
nest the original meta query and append the role meta query with an
AND relationship.

fixes #23849, #27026.

Built from https://develop.svn.wordpress.org/trunk@30094


git-svn-id: http://core.svn.wordpress.org/trunk@30094 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add a hidden submit button to the Appearance -> Header screen so keyboard users can submit the form correctly when a default image provided by the theme is in use.

Fixes #20880.
Props kovshenin, joedolson.

Built from https://develop.svn.wordpress.org/trunk@30095


git-svn-id: http://core.svn.wordpress.org/trunk@30095 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Better flexibility for 'type' in `WP_Comment_Query`.

* Add support for an array of values in 'type'.
* Introduce `type__in` parameter. This duplicates 'type' but is added for better consistency with other query classes.
* Introduce `type__not_in`.

Among other things, these changes will make it easier for plugin authors to
manage the appearance of custom comment types in various WP interfaces.

Props dancameron, mordauk.
See #12668.
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git-svn-id: http://core.svn.wordpress.org/trunk@30096 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: leading the way with support for title-tag

Props obenland, fixes #30146.


Built from https://develop.svn.wordpress.org/trunk@30097


git-svn-id: http://core.svn.wordpress.org/trunk@30097 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use `WP_Comment_Query` to query comments in `get_approved_comments()`.

Props dancameron.
See #12668.
Built from https://develop.svn.wordpress.org/trunk@30098


git-svn-id: http://core.svn.wordpress.org/trunk@30098 1a063a9b-81f0-0310-95a4-ce76da25c4cd