Changing to the MIT License

I don't suspect that this project will ever be particularly sophisticated. It's supposed to fulfill a simple need, the ability to make simple changes to MIDI files. As a result, I think it makes sense to allow people to take my code and integrate it into their projects because most of it will be relatively straightforward.

Besides that, to be honest, the only things I want from this project are a tool I'll use myself and resume filler ;-)