Move spinning cubes into its own scene object

This will make it easier to set up multiple test scenes and swap between
them for testing.
Load textures into GPU and use them when rendering

This isn't working quite right yet, getting no output on a textured
entity.
Make sure FreeImage gets initialized at some point
Fix bug in getUniformLocation where loc was getting shadowed

Loc was always returning 0 because loc in the if block was a new
variable in a new scope due to the :=. Now ensuring that I'm using
the location variable directly and returning the right values.
I've got a textured cube!
Fix small typo in view matrix calculation

This was leading to some really strange stretching that looked like the
Perspective was just off.