Vertex colors in OBJ files don't work

[cochrane]

Turns out that they are not 0-255 but floats in the nominal 0-1 range. So that needs to be supported (and I think it was at one point, but then I changed to a new parser and forgot about that).

For that matter, they are often outside the 0-1 range, with positive values to make things more lit than they'd normally be. That needs to be supported as well.