OPT: better registration parameters
OPT: better registration parameters

Former-commit-id: b2747556930d95ece73a075312e3a8331a376e9b
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox