REF: upgraded usage in parser. now possible to put multiple lines in description of options
REF: upgraded usage in parser. now possible to put multiple lines in description of options

Former-commit-id: 84a587eea87f0d01b645f2e8bf5229aa5636e016
Former-commit-id: fd8be2c9168b5adbb01009d85e6e5ed245f9e080
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox