DEV: trying to replace ants with antsRegistration for affine-- still need work
DEV: trying to replace ants with antsRegistration for affine-- still need work

Former-commit-id: e55c82181d9413cfbc88ff342552df1f92dafffb
Former-commit-id: 50a50182108c45a49c5a529af5bb01458b0f20b3
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox