NEW: option to use segmentations during registration (with pointwise)
NEW: option to use segmentations during registration (with pointwise)

Former-commit-id: b44e2c0128e02b0c1e7836d1c95f008f80dc3b90
Former-commit-id: 7500b3e818c5a8093343dd22ac6772fc367b1dc8
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox