Updated the syntax for rustc version 0.13.0-nightly and added a .gitignore

It's a syntax update (replaced `static` with `const` for global constants, `..` with `...` for ranges in `match`, etc.). Also updated the calls to the [rust-sdl2](https://github.com/AngryLawyer/rust-sdl2.git) library to bring it inline with the newest version. Finally, I added a `.gitignore` to ignore the `target` directory and `Cargo.lock` when add files to the staging area.