OPT: regiser_multimodal: added flag -owarp to specify output warping field
OPT: regiser_multimodal: added flag -owarp to specify output warping field

Former-commit-id: 589620444dbef2d545c64eab6f327548b4dc1a89 [formerly 98dba539a08d91439e7eb9ea2ae8a0e147f23b91]
Former-commit-id: 76c35f63bc99ea4847d92bffd23a1a726a0b51b4
Former-commit-id: 94e1d9476ed498a6970c93ed91469107634f77f8
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox