Allow special groups in default user permissions

- Use ACLFormatter in ACL::getDefaultUserPermissions
- Remove ACL::fixACL
- Add return value to Contact::pruneUnavailable

src/Model/Group.php

@@ -384,7 +384,7 @@ class Group
 		DBA::close($stmt);
 
 		if ($check_dead) {
-			Contact::pruneUnavailable($return);
+			$return = Contact::pruneUnavailable($return);
 		}
 
 		return $return;