Revert "Add initial biker sprite implementation"

This reverts commit ecabf111db138f059e01b32aed8097bbe1b36974.
Merge branch 'master' of https://github.com/PostRockFTW/ExcitingBike
Handle the quit event. Tweaks to keydown process.
Merge branch 'master' of https://github.com/PostRockFTW/ExcitingBike