Dots in user names.

[Chuck Yerkes <chuck+obsd_(_at_)_2003_(_dot_)_snew_(_dot_)_com>]

Default adduser (and the /etc/security script) disallow . in
user names as non-first chars.

I changed that (simple regex tweak - not worth a patch).

The ".", IIRC was bad because the non-POSIX chown and chgrp parsed
user.group on it.  POSIX dictates : is the separator.

You can certainly add a user with a ".", but chown wants 
SUPPORT_DOT removed from chmod's Makefile).

I haven't found problems and it's made it easier to support
mail address like "first.last" as account names for mail-only folks
and website "owners" like "www.example.com".

It may be rushed, but is there a reason to support "." as a user/group
separator in 3.3?