Add ability to send multiple messages at once

Hi, are you accepting pull requests? If so, this still may be a stupid addition or simply beyond the scope of what Carrier Pigeon should do. But I'm trying to use Carrier Pigeon in another project, and this simple addition would be a great help, so perhaps it would help others as well. Feel free to reject this if you don't feel like dealing with it for any of the reasons mentioned above (or any othe reason). In that case, I'll just continue with the fork. Regardless, thanks for the gem! It's great to have such a simple way to interact with IRC, and I use it often.