Make cascading better so that ttywatch can talk to remote telnet daemons --
right now it can only talk to remote ttywatch instances because of the
limited implementation of the telnet protocol.  However, it is very
important to me to keep the telnet implementation light and simple;
just barely enough to function, no extras.

Perhaps all dev_fd should be non-blocking -- perhaps the write queue
could fill up on a machine being logged and stop ttywatch.

If someone could add PAM authentication for incoming network connections,
that would be nice.  I just don't need it, myself.  Needs to not block --
needs custom conversation functions that store state in net_conn.

Should add SSL encryption/authentication.  Should be compatible with
ssl-telnet if at all possible.  Any takers?

I'm not completely happy with the port locking option semantics, and
I reserve the right to change it later.
