Ensure the mixed type of `string|int` is reflected on the `$title` parameter in `wp_die()`.

The ability to pass an error code as short-hand to the `$title` and `$args` parameters was added in r30355. Changes also include cleaned-up formatting and line-wraps for other documentation in the DocBlock.

See [30355]. Fixes #10551.

Built from https://develop.svn.wordpress.org/trunk@30379


git-svn-id: http://core.svn.wordpress.org/trunk@30376 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Clarify/correct inline documentation in wp-includes/l10n.php.

* Add a missing `@return` description for `load_default_textdomain()`
* Clarify the `@param` description for `$locale` with an inline `@see` tag
* Ensure the correct parameter variable is used when documenting `$args` for `wp_dropdown_languages()`

Props camdensegal.
Fixes #30385.

Built from https://develop.svn.wordpress.org/trunk@30380


git-svn-id: http://core.svn.wordpress.org/trunk@30377 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add missing documentation for the `$password` parameter, passed to the `check_password` hook.

Props coffee2code.
Fixes #30311.

Built from https://develop.svn.wordpress.org/trunk@30381


git-svn-id: http://core.svn.wordpress.org/trunk@30378 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add some missing inline documentation for methods in the `WP_Widget` class in wp-includes/widgets.php.

Props ericlewis, jazzs3quence.
See #30315.

Built from https://develop.svn.wordpress.org/trunk@30382


git-svn-id: http://core.svn.wordpress.org/trunk@30379 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Improvements to `wp_make_link_relative()`.

* Support relative URL input.
* When the URL being made relative has another URL as a parameter, don't make the second URL relative.

Props voldemortensen.
Fixes #30373.
Built from https://develop.svn.wordpress.org/trunk@30383


git-svn-id: http://core.svn.wordpress.org/trunk@30380 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Background Updates: Introduce support to take advantage of Group Writable (or World Writable) to Core Background updates.
This is only enabled when new files will not be installed during the update (as indicated by the WordPress.org API), and does not apply to Plugin/Theme/Translation Background Updates.

Additionally, the code to determine if the 'direct' filesystem transport should be used has been tweaked for wider support (where getmyuid() was unavailalbe) which fixes #10424

See #10205, #30245

Built from https://develop.svn.wordpress.org/trunk@30384


git-svn-id: http://core.svn.wordpress.org/trunk@30381 1a063a9b-81f0-0310-95a4-ce76da25c4cd