NEW: added functions to pass from pix coordinates to phys coordinates and vice versa
NEW: added functions to pass from pix coordinates to phys coordinates and vice versa

Former-commit-id: d604fed2dddd76ebb73911a8aa4d00f05041a035
Former-commit-id: 60b90627a2ff5d620ac22882d64d2d05ad7db273
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox