lock. (This bug has always been there, but didn't matter before;
maybe pthreads changed.) Comment out self-spawning stuff until can
fix df-transfer problems. Other minor changes around logging.
send player counts, local and expected. Based on these the relay
accepts connections, declares the game full and ready for message
forwarding, and decides whether to accept a reconnect.
scheme where cookie is used only to connect, and is replaced for
reconnects by a relay-generated name that's supposed to be unique
across all games on all relays and includes a hostname read in from
config file; relay assign non-servers' hostIDs.