REF: now using TensorFit methods instead of calling wrappers
REF: now using TensorFit methods instead of calling wrappers

Former-commit-id: 058c26faaa241b637bf367afe7f6557b1ac1b24d
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox