NEW: msct_gmseg_utils: developing group wise registration of the target to the model space (work in progress)
NEW: msct_gmseg_utils: developing group wise registration of the target to the model space (work in progress)

Former-commit-id: 7ba7e570f9f268ea4211ba98cc5591be0efac9ed
Former-commit-id: 76c9385347874c6dd5c5700cd7f6102d6850b284
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox