Merge pull request #275 from Coeuvre/master

Add a preliminary AudioBackEnd which is able to play sound
Merge pull request #280 from Coeuvre/master

Added doc comments
Merge pull request #282 from Coeuvre/master

Can play music now
Added rust-sdl2_mixer docs

Closes https://github.com/PistonDevelopers/piston/issues/276
Port to rust-image
Fixed Texture
Merge pull request #284 from bvssvni/master

Fixed Texture
Added how to generate target folder
Removed chapters, added how to build examples
Update tutorial.md
Update tutorial.md
Added link to rust-image docs

Closes https://github.com/PistonDevelopers/piston/issues/286
Added how to render with OpenGL
Added link to tutorial

Closes https://github.com/PistonDevelopers/piston/issues/288
Updated Readme.md to use www.pison.rs.
Merge pull request #289 from leonkunert/master

Updated Readme.md to use www.pison.rs.
Removed Rust-png from the dependecies.
Merge pull request #295 from leonkunert/master

Removed Rust-png from the dependecies.
Updated link with list of games

Closes https://github.com/PistonDevelopers/piston/issues/296
Fixed a bug that can't load sound/music in Game triat