new user id system idea.

[John Pierce]

I've found that expending some effort in making sure group ownership of
directories is reasonable and in using 4.2's "member of multiple groups"
feature has solved most, though not quite all, of the problems we used to
have with permissions.  Addition of a system call to allow "group superusers"
helped quite a bit [if uid == gid, then that user can work their will with
that groups files].  While there are still occassions where I would really
like to have "subgroups", on a practical level I haven't yet found anything
to be unmanageable.