added Wolfy87's EventEmitter library as a submodule
refactored SocketClient to be based on EventEmitter.
refactored Chat to be based on EventEmitter and wrap parts of the new SocketClient, so other code can build on Chat instead of using the more low level SocketClient functions.
added a new ivar serverSignature to User, which will always hold the signature as transformed by the server, whereas User.signature shall only hold the user generated signature.
changed socket-server.js to reply with the transformed signature.
changed ui.js to use the new APIs, enabling nick and signature changes while being connected.