Imported from archive.

* mudpy.py (User.enqueue_input, User.negotiate_telnet_options):
Implemented a real Telnet option negotiation stack, paving the way
for more robust client integration.
(get_echo_sequence): Refactored echo handling in password prompts to
rely on Telnet option negotiation.
(get_menu): Added an RFC 885 end of record prompt terminator for
improved MUD client support.