OPT: added check and completion of centerline #32
OPT: added check and completion of centerline #32

Former-commit-id: 966829b01112950d6d2b898fe0017bde83aa0320 [formerly 7a96998662c403195c6cc53d239264ca480c284f]
Former-commit-id: 57253f8cf1e2906d03483e6ce34b52414c0f43d2
Former-commit-id: 334da81c0a1b8a07df02add945e67a4ef58ea7a5
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox