Connection can be made "ready" via a method call.
Moved parsing back into dispatcher.

Not sure about this.

I like the dispatcher processing most of the irc requests.

The only ones we don't are 001 which we use to trigger connection
ready and the ping/pong thing.
Added a write queue with its own thread.

IRCConnection#write is thread-safe as long as we lock around shared
start like @instance variables etc.