Fix C++ API GraphicsModule::getMaterialModule, was getGraphicsMaterialModule. Issue 3589.
Fix C++ API GraphicsModule::getMaterialModule, was getGraphicsMaterialModule. Issue 3589.

OpenCMISS/zinc,hsorby/zinc,hsorby/zinc,hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc