Update for latest nightly + README, .gitignore

Wanted to fool around with the code, so I got it in fighting shape.

I'd like to do some other things (for a future PR), such as:

* pick a build system (`rust-empty` or `cargo`.. probably the former. is that ok?)
* add some tests
* save the world

Could I trouble you to create some tickets with unimplemented functionality (e.g. I know it doesn't preserve comments, but what else could be improved), since you know this stuff better than I?

Also: needs a license.. If you'll pick one and put it in a `LICENSE.txt` file, I'll add the notices.

Thanks