Replace old parser with irc-message module.

I've been working on a lot of IRC-related modules for node recently. Most spawned from not liking how node-irc does things, or being unhappy with it performance wise (i.e. when handling a ton of sockets/data).

As I was in the process of creating a client library to replace node-irc for my needs (which I've since discarded), I created a super efficient IRC message parser.

I've released this as a separate module on npm, called `irc-message`, you can find out more [here](https://github.com/expr/irc-message).

This pull request is a small rewrite of the parseMessage() function to make use of `irc-message`. It's completely backwards compatible with the data the old parser produces, but offers up to **3 times better performance**. This is mostly due to getting rid of regular expressions, amongst many other optimisations I've made when writing it.