Merge pull request #149 from bvssvni/master

Modified user input example to print mouse button events
Merge pull request #150 from bvssvni/master

Fixed SDL2 key down bug
Merge pull request #151 from bvssvni/master

Fixed ambiguous names in `keyboard`
Merge pull request #152 from bvssvni/master

Added support for full keyboard for GLFW
Added chapter for 'Drawing with OpengGL'
Updated to latest Rust