OPT adapt batch_processing to new outputs of sct_register_graymatter
OPT adapt batch_processing to new outputs of sct_register_graymatter


Former-commit-id: 6b46f2a045d95eb09a73ee806c8c1bc37ab75a60
Former-commit-id: 7d9cc7b7f5c3e5a16dd1398eaeba0b4ff69b517d
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox