Don't freeze the message; messes up commands.

lib/message-parser.js

@@ -43,7 +43,7 @@ var MessageParser = function MP (receiver, socket) {
     var parser = Object.create(EventEmitter());
 
     parser.parse = function (raw) {
-        var message = Object.freeze(new Message(raw, receiver));
+        var message = new Message(raw, receiver);
         this.emit(message.command.toLowerCase(), message);
         this.emit("*", message);
         return message;