`WP_Query` was only missing one access modifier.

Add access modifier (`public`) to applicable class methods/members of `WP_Rewrite`. I am not brave enough to set some of the `var`s to `private` without more testing.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28533 602fd350-edb4-49c9-b593-d223f7449a82