This allows to work around removed CubeGeometry sides functionality.

Now we can finally mess with car materials directly in the scene file.

Also, removed webgl_trackballcamera_earth as there is already a example showing the usage and another one using this scene.

Also, removed GeometryLoader. I'll try doing the JSONLoader to GeometryLoader change again in the future.

@alteredq: I'll try to tackle Minecraft AO next.

See #2623.

Without CubeGeometry is a little bit easier to follow. Wasn't sure whether doing it like this or using a single material/texture with modified UVs per side.
Also, I've had to comment out some code from GeometryUtils that asumed object2 to be a mesh.

This way the panel illustrates the API better.
It's not too intuitive but eventually the (future) helper will probably make it uneeded.

Ok, lets go with blue.