Day 111: Little improvements to batch shadow

Today I had the revelation that the shadows cannot work with my new batch.
That's because the batch uses the shaders of the models, while tha shadow must use the same shader for everything...this requires to use the old batch, there's no way around it. I did a few changes to make it a little simpler and faster, because it will never change, so it doesn't need to be versatile.

Lighting however will work pretty well with the new batch I think, because the models will be the bounding boxes of the lights, and each one of them will have a user defined shader.
Right now it is not even using a batch, it draws each model with a single draw call, so everything will require quite a bit of refactoring, but it should work in the end.