avoid to degenerate the view frustum if there is only a single point in the scene
avoid to degenerate the view frustum if there is only a single point in the scene

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