Extension:GroupPermissions

Extension:GroupPermissions allows preset $wgGroupPermissions to be changed internally.

Usage
Put those two lines as is at the VERY END of your LocalSettings.php file, this will allow GroupPermissions.php to read/write its changes to settings.php, any changes to the $wgGroupPermissions array may or may not be included in the special page.

To edit those settings the user MUST be a bureaucrat, anything else will only get read permissions.

To access the page, goto special:GroupPermissions

Future Updates
A new version will be released with HUGE updates, it will involve being able to create and remove groups (except the main groups) and add/remove permissions for those groups.

Will eventually use Ajax for the extension, should comply with the layout of other Mediawiki Special Pages.