* Introduce delete_with_user flag to register_post_type
* Set delete_with_user to false for the nav_menu_item post type
* Set it to true for all other core post types
* If delete_with_user is not set, fallback to post_type_supports('author')
Props nacin
Fixes#16358
git-svn-id: https://develop.svn.wordpress.org/trunk@20739 602fd350-edb4-49c9-b593-d223f7449a82