Fix some issues in filling zones normals.
Fix an issue with some models that have materials but didn't defined the diffuse color.
Workaround for Bug #1443431.
Implement some missing "code logic" for pervertexperface normals.
Remove some not used functions.
Calculate normals using double type.
3dviewer: back to double (from float) in class S3D_MASTER for 3 members (m_MatScale, m_MatRotation, m_MatPosition) which are used in dialogs and r/w file functions, which expect double.
Using float create minor but unwanted issues in r/w file functions.
S3D_MATERIAL: enable all color options: if a 3d shape has bad color parameters, the shape must be modified, not the 3d rendering.
The rendering now matches what we see in other vrml viewer like FreeCAD.
Some minor coding style fixes.