Slug meta box should be added as supported parameter for CPT and post_type_support

[wycks]

When registering a CPT there is no parameter to remove the slug meta box.

Setting:

 'public' => false, 
  //Removes the permalink edit box but does not remove the slug meta box
 'rewrite' => false,
  //Also does not remove the slug meta box and still allows for editing the slug?

Possible solution:
Add a new supports parameter 'supports' => array('slug-box'), when registering a CPT

Furthermore it is confusing in conjunction with the edit permalink problem(related #18523 ).

[helen]

Can we work on just removing that metabox entirely, as suggested in #18523?

[nacin]

The slug meta box is required to support permalink changes using the fancier UI near the title field. So, this is a duplicate of #18523.