MAX_LIGHTS should be dynamic, and equal to number of lights

[michalbe]

RIght now, in the fragment ubershader we're setting max number of lights to 100. And because there is a maximum number of uniforms limited by the GPU, this should be dynamic. There are probably two simple ways of solving this:

• user specified max number of lights, passed for instance to the Game constructor
• counting number of lights and recompiling shader each time the number changed (since this should happen for all the material instances, I would vote the first one).