OPT: add information to the header of the output file (date, time, metric file, method)
OPT: add information to the header of the output file (date, time, metric file, method)

Former-commit-id: 74d62e6a05ac5276608419cf3cd6f38e50dcfb45 [formerly 17a6964acac48d9cd95c28151ae725444dca0d0e]
Former-commit-id: 3746a2188e364c0b163a8fcbb9996d2ca0067cd4
Former-commit-id: e3cd8f22fe0f36059abcdcd102ae656fd8807342
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox