Merge pull request #67 from bvssvni/master

Upgrade to latest rust-sdl2
Updated to match SDL2 updates
Merge pull request #68 from AngryLawyer/update-to-latest-sdl2

Updated to match SDL2 updates
Updated README.md, closed #72
Merge pull request #73 from golergka/patch-1

Updated README.md, closed #72
Renamed to sdl2_window

Closes https://github.com/PistonDevelopers/sdl2_game_window/issues/74