Support Vertex Color OBJ Format

[arpu]

Hey, would it be possible to add support for #obj file generated by SculptrVR #Vertex format: v x y z r g b#Vertex colors are not supported by all programs.

sample is https://www.shapeways.com/forum/t/vertex-color-obj-format.42061/

[thisistherk]

Yep, sounds useful. Probably be a while before I'll get around to it though. Happy to take contributions in the meantime :)

[arpu]

this would be greate! @zeux could add this to meshoptimzer using fast_obj

( i have to less knowledge for a PR :/ )

[maxrigout]

@arpu I've created a PR for this issue, feel free to check it out and let me know if you find any issues :)