Go with plain names for factories

No need for the "New" prefix, that would just get tedius after a while.
The "factories" prefix on the call will be enough context.
Add beginning support for loading cubemaps from files

Right now plan on using this for a skybox. Will need extra work if it's
to be used for reflective cube-maps.
Add cubemap material files and hook into TexturedCube scene

Commented out because it doesn't work quite yet (the vertex structure
for the cube map isn't ready yet and will just show a black screen).
Add Skybox mesh and hook up glDrawElements

This probably also isn't working but I'm getting there!
Update cubemap shader to match uniform name
Load skybox mesh into memory and enable in the scene

Still just shows black background but at least the other textured cube
shows up properly.