Allow true object chaining by cloning the emitter object when the config...

Hi @nulltask,

This patch will allow users to do things like

    emitter.in("my room").emit("hello").emit("world")

and

    my_room = emitter.in("my room")
    emitter.emit("this goes to everyone")
    my_room.emit("this just goes to my room")

Please let me know if you'd like me to work on it further.

Cheers,
@mogest