OPT: register_multimodal: working for affine
OPT: register_multimodal: working for affine

Former-commit-id: 1c38ba082f17ce0e816d02074ca14612d658ee5e [formerly d9100cf02daae9b924a6e4d07c8ea57b803cfe6e]
Former-commit-id: d06f5b30f64171634d6ec1711bde61fbe48a4826
Former-commit-id: 0ddea0b8e1de3f13d3f4a19cf4346f853909b39c
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox