Merge pull request #24 from bvssvni/master

Changed back to original rust-sdl2
Fix bug where repeated key events would lag other events
Make struct internals public
Merge pull request #25 from bfops/master

fix laggy event bug; expose window struct members
Implemented `close`

Closes https://github.com/PistonDevelopers/sdl2_game_window/issues/26