Need more control with global settings for Wiki

Need global settings so can hide the tick boxes for who is allowed to edit wikis.

Currently even a contributor can see and update this info whether you want them to or not.

There should be a setting to hide this from the front-end for only admin and editors to see.

Also probably should be able to hide the tick box for 'Enable e-mail notifications' otherwise anyone can turn it off or on.

Cheers.