Fixed a typo in an error message (--sw_renderer -> --sw-renderer)
Fixed a typo in an error message (--sw_renderer -> --sw-renderer)

prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r