Removed some unused/obsolete messages:

Removed some unused/obsolete messages:
group-admin-desc, group-admin-name, group-anon-desc, group-anon-name,
group-bureaucrat-desc, group-bureaucrat-name, group-loggedin-desc,
group-loggedin-name, groups-addgroup, groups-already-exists,
groups-editgroup, groups-editgroup-description, groups-editgroup-name,
groups-editgroup-preamble, groups-existing, groups-group-edit,
groups-lookup-group, groups-noname, groups-tableheader,
group-steward-desc, group-steward-name, savegroup