Start: [skip ci] replace QTextStream and its manipulators with stringstream to avoid deprecation warnings with Qt 5.15
Start: [skip ci] replace QTextStream and its manipulators with stringstream to avoid deprecation warnings with Qt 5.15

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