Proper RFC 1143 Telnet option negotiation queue.

Proper RFC 1143 Telnet option negotiation queue.

* lib/mudpy/__init__.py: Added telnet to the modules list.

* lib/mudpy/misc.py (Element.send, User.__init__)
(User.adjust_echoing, User.enqueue_input, User.flush)
(User.replace_old_connections, User.send, check_for_connection)
(get_echo_sequence, handle_user_input): Minor adjustments to
accomodate new code in telnet.py.
(User.negotiate_telnet_options, telnet_proto): Moved to telnet.py
and reworked option negotiation stack to eliminate a possible loop,
bringing the code fully in compliance with the "Q" method described
in IETF RFC 1143.

* lib/mudpy/telnet.py: New file for constants and functions related
to support of the Telnet protocol.