OPT: now takes the last warping field space as reference. Does not work if last warping field is an affine transfo...
OPT: now takes the last warping field space as reference. Does not work if last warping field is an affine transfo...

Former-commit-id: 457efa985fb147bfe1d6244c86b099ad0cb33923
Former-commit-id: eb9e37916e7770e24f131432f5e0f0ca14942910
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox