refactor sct_smooth_spinalcord
refactor sct_smooth_spinalcord


Former-commit-id: 3d640a6181a71ff6a77409b9b408474721ae0c43
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox