1) Don't use socket.recvline() on non-blocking sockets.  Instead, have
   the recvq object parse lines and receive 64k at a time.
2) Pass all received data through the recvq object rather than attempt
   to process one command per recv().
3) Pass all data sent on established connections through the sendq
   object rather than only use it if send() fails.
4) Move client throttling completely into ircd_user.js and out of
   the queue processing function so we don't accidentally throttle
   server connections.
5) send() the entire sendq contents as a single send() rather than one
   line per main loop.
6) Parse the entire recvq each time through the main loop.  This
   requires tracking when an unregistered connection is replaced by
   either a client or a server connection.