importDWG: use libredwg's dwgtodxf converter if available
importDWG: use libredwg's dwgtodxf converter if available

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