FEM: vtk tools, small code change and comment in the regard of FreeCAD.Vector length
FEM: vtk tools, small code change and comment in the regard of FreeCAD.Vector length

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