added test to make sure not to crop outside of slice range (fixed #1811) (#1813)
added test to make sure not to crop outside of slice range (fixed #1811) (#1813)



Former-commit-id: d7474e82af6acf9dbfbabb9fd8b797fc1156244d
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox