Add message parsers

[meshy]

These should be useful for handlers. They can either be used to deconstruct messages in handlers themselves, or to make a handler decorator that passes the more semantic arguments into handlers that know what they're getting. eg:

def parse_privmsg(message):
    """Separate a PRIVMSG string into semantically named parts."""
    return {
        'text': message.suffix,
        'sender': message.prefix,
        'target': message.args[0],
    }

This could probably have a better name than parse_privmsg.

[meshy]

Come to think of it, is "parser" even the right word?

[meshy]

The example should probably also list channel.

It should be noted that in 1-to-1 conversation, it may be best to list the sender as the channel, whereas for conversation in an actual #channel, the channel should be the target.

[meshy]

Come to think of it, is "parser" even the right word?

Well, I can't think of a better word.