Add `public` access modifier to methods/members of `WP_Widget` and `WP_Widget_Factory`.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28527 602fd350-edb4-49c9-b593-d223f7449a82
Add access modifiers to `WP_User_Query`.

Add magic methods for BC: __get(), __set(), __isset(), __unset(), and
__call().

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28528 602fd350-edb4-49c9-b593-d223f7449a82