change the set listened on. There's still some debugging to do but
nothing that worked before is broken. Also begin to accept unique
prefixes (e.g. g for get) for commands and attributes on the control
port. Note that relay-related code in comms seems broken now, but is
without this checkin.
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.
