REF: straighten_spinalcord: minor changes
REF: straighten_spinalcord: minor changes

Former-commit-id: ab3d7ad846d8298ea471a5d074b8cc5864e0d48f [formerly 079256b7269643455683db1e93c34358b014b31a]
Former-commit-id: 508324e0d21615271f0e7278207d5614722b7de2
Former-commit-id: 096041330e06139b1b7d0d7f7d29327d674530ad
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox