OPT: now separating first and second registration algorithms in sct_register_multimodal
OPT: now separating first and second registration algorithms in sct_register_multimodal

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