OPT: msct_gmseg_utils: now allow only 1 scaling factor for the group wise registration
OPT: msct_gmseg_utils: now allow only 1 scaling factor for the group wise registration

3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox