we introduced non-blocking writes; however, being non-blocking when the
goroutine has no buffer means that many messages will be considered
lost.
This commit change from "non blocking" to "max 500ms; first timeout
means stop it all"; it also put a little buffer on client messages.
before this there was some hidden race condition because raceCondition
is not concurrent-safe, and there was some concurrent reading and
writing.
Now everything is handled safely by the Hub.
Client now have "options" which are understood by the Hub to handle
them differently.
