Added an example about sprite
Merge pull request #67 from Coeuvre/master

Added an example about sprite
Fix the aspect ratio in the gfx cube example

An aspect ratio of 1.0 does not fit the screen resolution, so the rendered cube
looks a bit odd. While fixing this the relation has also been refactored.
Merge pull request #68 from aepsil0n/fix/aspect_ratio

Fix the aspect ratio in the gfx cube example