Misc. source comment typo [skip ci]
Misc. source comment typo [skip ci]

Found via `codespell`
[skip ci]
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