Update Geometry3D.js

Fix for #168.

When colorPerVertex is FALSE and colorIndex is empty, colors are now derived from face indices, they are not taken from coordIndex any more.

Normals suffer by the same syndrom. When normalPerVertex is FALSE and normalIndex is empty, normal indices are taken from coordIndex. It is also wrong (please see the specification), but this pull request does not fix this.

Texture coordinates should be OK. When texCoordIndex is empty, texture coordinates really should be taken from coordIndex.