The Quake game loop in Pythonic pseudo-code, mostly from `host_frame'.
Thought this might help get the client side smoother, but guess Quake
does things too differently.  Probably ought to look at QW instead.


looping at a fairly constant speed:
	get input events
	poll network
	if listening server:
		send client messages	# movements, etc.

	# Server ops
	if server:
	   check for new clients
	   read client messages and do thinking
	   do physics
	   send messages to clients

	# Client ops
	if pure client:
		send client messages  	# i.e. after incoming messages have been read
	if any client:
		read data from server	# and update state
	update video and audio
