NEW: Complete tray matter segmentation pipeline
NEW: Complete tray matter segmentation pipeline

Former-commit-id: 1de73da1e9340194a595946f2a82cfb77d602695
Former-commit-id: 34248615dcf141f452b44f65256da5fae6faa413
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox