Light parameters

[gjcope]

In the (to my knowledge) currently available version of the draft 4.0 spec, the only defined light parameters are color, intensity, and angle (for spot lights). I may be remembering incorrectly, but I thought we had more previously defined? I also recall their being defined defaults for some as well. Apologies if I'm looking at the wrong document.

One parameter I'm particularly concerned with is "decay". If undefined, different default values in different implementations could end in drastically different results - from a well light scene to scene that appears to have no light at all. The scenario currently happens easily in the viewer I support (Voyager).