[fixed] Couldn't reproduce at importing completely an .obj file that has vertex color

[micheus]

JFYI, the '.ply' importer was added to Wings3D project and the issues I found were fixed.
I caught a sample file from the internet; imported it to MeshLab and painted it; then I imported it in Wings3D:


Now, the vertex color should be properly imported to Wings3D by any importer that handles it.