Specular nonsense

I’ve had specular reflections on the brain a bit recently. Decided to get off my lazy butt and add it to Chickens.

There are three new functions:

cluck_set_spec_camera_position(x, y, z)
cluck_set_spec_strength(strength)
cluck_set_spec_exponent(exponent)

You can probably guess what they do but otherwise the documentation is here.

Also disabling lights was behaving badly on HTML5, so I hopefully fixed that.