Revisit performance improvements of the 3D shaders

Adding self-illumination color and removing the restriction of 3 lights will incur performance costs, Performance improvements should be relooked at. The shaders contain commented out code for different implementations that differ by performance.

One pitfall to look out for is floating point comparisons. The shaders don't behave like Java, and from rudimentary tests it looks like it's a bad idea to do so. Introducing a delta seems to be more accurate.