Pass the taxonomy around to relevant nav menu actions to avoid arbitrarily deleting all items with `menu-item-type` of `taxonomy`. Adds unit test for `wp_get_associated_nav_menu_items()`.

Props garyc40, SergeyBiryukov.
Fixes #15264.



git-svn-id: https://develop.svn.wordpress.org/trunk@25163 602fd350-edb4-49c9-b593-d223f7449a82
Search term `name` and `slug` when the `search` arg is passed to `get_terms()`. Adds unit test.

Props wojtek.szkutnik.
Fixes #13992.



git-svn-id: https://develop.svn.wordpress.org/trunk@25164 602fd350-edb4-49c9-b593-d223f7449a82