OPT: changed default values (DWI group and spline reg)
OPT: changed default values (DWI group and spline reg)

Former-commit-id: 4c81058ebe281bdc91e7eda07536f927a7a0f319 [formerly 0b734438d99fde20628685182d4d802ae40c7f12]
Former-commit-id: 80fcd4bb323a09c0d1eaa54ad7943bf8c1f0615e
Former-commit-id: 166eb80e6062b736fca1685b6f0e7c39ee586e47
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox