Added vertex cache to voronoi colorExterior callback processing - cuts execution time in half.
Added vertex cache to voronoi colorExterior callback processing - cuts execution time in half.

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master