NEW: compute_similarities(), label_fusion(), and warp_back_seg()
NEW: compute_similarities(), label_fusion(), and warp_back_seg()

Former-commit-id: 53788767063291fe25964c474743d775894bddcf [formerly b6086b8cff686fff0fa2a76dc49f78d7441266e8]
Former-commit-id: ab7a387533cd2489e639a56357e3b891d9171a64
Former-commit-id: 640ceb54c979bfd7588290673539df52d694547f
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox