* src/ttt-args.h:
* src/ttt-args.c: (ttt_args_help), (ttt_args_parse): Add a -u,
--user option for controlling the uid under which the server
process runs.
* src/ttt.h:
* src/ttt-server.c: (ttt_server_register_client), (main): Recert
the dup of stdout which wasn't working. Instead just print client
join information on stderr so that it goes into the log. Implement
support for the user option by calling setuid to drop root
privileges the process might start out with.