REF: removing resample flag and introducing a speed factor flag
REF: removing resample flag and introducing a speed factor flag

Former-commit-id: 751575c466b3584d4cce4b5877f8c6c8f3ded9da
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox