Server now suspends disconnected clients.  Once it detects all clients
have disconnected, the Server closes.  Need to do:
*Special handling if the host client closes; this (probably) should
terminate the server too.
*Suspend needs to be fleshed out so that the disconnected player isn't
just a sitting duck.
*Dean's concurrency additions will need to preserve the disconnect
handling.
*Concurrency should also facilitate reconnect.