NEW: new option in sct_crop_image. Possibility to crop with minus values.
NEW: new option in sct_crop_image. Possibility to crop with minus values.

Former-commit-id: 895dba13304379a3be273805e0fd38feac756f5f [formerly 8217f51dbf31fcc988e3a8d1da2eb540338a5261]
Former-commit-id: f85b5c238101d65e16463a066e5dd4400d333395
Former-commit-id: edbd7965ef50f3513697fa380f6cf4055963d90f
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox