Merge pull request #138 from bvssvni/master

Fixed current directory bug in `load_image`
Merge pull request #142 from bvssvni/master

Updated example in slides
Merge pull request #146 from Coeuvre/master

Added all SDL2 keycode to `keyboard::Key`
Create tutorial.md
Merge pull request #147 from Coeuvre/master

Added an example to print 'keyboard::Key' when pressed a key
Added titles for each chapter in tutorial
Modified user input example to print mouse button events
Merge pull request #149 from bvssvni/master

Modified user input example to print mouse button events
Fixed SDL2 key down bug

Closes https://github.com/PistonDevelopers/piston/issues/148
Merge pull request #150 from bvssvni/master

Fixed SDL2 key down bug
Fixed ambiguous names in `keyboard`
Merge pull request #151 from bvssvni/master

Fixed ambiguous names in `keyboard`
Added support for full keyboard for GLFW
Merge pull request #152 from bvssvni/master

Added support for full keyboard for GLFW
Added chapter for 'Drawing with OpengGL'
Updated to latest Rust
Updated game loop
Upgraded to lastest rust: StrBuf to String