setuid, because after we setuid we don't have the priviledges we
  need to setgid anymore, duh.  merged switch_user() and
  switch_group() into switch_id(), since that code has to be wound
  together.

- return -1 from switch_id() if it's not defined to do anything else.

- moved daemoinize(), write_pidfile(), and switch_id() from main.c to
  util.c


svn:r656