OPT: create inverse warping field
OPT: create inverse warping field

Former-commit-id: 0be92110f9d2f539561b949d2c7e48399229fa6a [formerly f032933187d5482124dc9964b9f638759755ea56]
Former-commit-id: d44ef9106d2dfde75491592132513a9f1a5678c3
Former-commit-id: 835ee53728784df5a71151daa0c4e5c529ce159e
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox