TEST:  testing of sct_register_gm_multilabel  in comment for now (testing_data not up to date yet)
TEST:  testing of sct_register_gm_multilabel  in comment for now (testing_data not up to date yet)

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