REF: ensures retrocompatibility of sct_straighten_spinalcord
REF: ensures retrocompatibility of sct_straighten_spinalcord

Former-commit-id: 304708ed3ed6cba5e3f542ffcecb1b01f12b094b
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox