Fix POV-Ray mesh export
Fix POV-Ray mesh export

Actually writes the mesh (which was computed but never written)
Fix export of texture colors, including transparency

Signed-off-by: Geoff Hutchison <9cf35bacc9f8512ca007341c9e919cf5dc03e0c7@gmail.com>

OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs