REF: use parser to generate error and display usage
REF: use parser to generate error and display usage

Former-commit-id: 393ac3476165a9e95321bf6e4b92e79a2c41daba [formerly 723bcccf0d4aab059bd858e52854ca4bc90fb1e2]
Former-commit-id: d932f3dcf14d88621bfedde86975f9e446b2add3
Former-commit-id: 89c98b6ae7422c38d9c5c23de4cb53fc38a7c0be
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox