OPT: now possible to create cylindrical and gaussian masks
OPT: now possible to create cylindrical and gaussian masks

Former-commit-id: 4d1e026b0701317237aa0d18efb32486501d0e03
Former-commit-id: a199eaf3c2a62099428dfc87a2cbe278833424ae
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox