Forumlar / Cotonti / Core Labs / Ideas / Groups without rights table

This could be implemented in combination with this hack, as Trustmaster pointed out.
This hack adds grp_type to the sed_groups table, with possible values of 'both' and 'sub'. If set to 'sub', this group can only be set as a subgroup (not main).
It shouln't be too hard to add the option 'rightsfree' (or similar) for groups which don't require a sed_auth row.