Added local lights to avatar. Added haze to voxel.

Initial test values for haze distance and color, as well as light direction and color.
In particular, since the haze color and distance don't currently change, it's probably clearer just to define them as constants rather than members: "const glm::vec3 HAZE_COLOR(0.24f, 0.27f, 0.34f);" above first use.  When we allow changing them, that can change to DEFAULT_HAZE_COLOR.