#473 Export to U3D fails to create u3D file

[Miguel]

I've noticed that if I edit the texture file and save it with a bit-depth of 32-bit instead of 24-bit, then the Export as U3D will not work. It will create the tex file but not the U3D file. It seems that if the png file is saved with 24-bit it works.

[Miguel]

Also note that Meshlab operations like Transfer: Vertex color to texture save the image in 32-bit, making the U3D not work.