OPT: msct_parser : changed the length and pad for the description lines (same change than in master)
OPT: msct_parser : changed the length and pad for the description lines (same change than in master)

Former-commit-id: 39cc0a520e54e842c649e0282aa8e5b878d1995d
Former-commit-id: 60b52f840e9f0ff231826a88bb6c2c5fce814af0
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox