Merge pull request #5 from superfunc/master

Add dead code elim pragma to accomodate those running 2.0.0
Added example which renders a cube in OpenGL; Improved existing skeleton
Merge pull request #7 from trustable-code/master

Added example which renders a cube in OpenGL; 
Improved existing skeleton
added audio module, cleaned up case inconsistencies in sdl2 and sdl2/gfx
Merge pull request #8 from fowlmouth/master

added audio module, cleaned up case inconsistencies in sdl2 and sdl2/gfx
Added example program for audio output

A simple sine tone generator
Fixed formula in example
Removed unused variable in audio example