OPT: straighten_spinalcord: set robust=0 and resampling of segmentation with trilinear
OPT: straighten_spinalcord: set robust=0 and resampling of segmentation with trilinear

Former-commit-id: 08ef0d97c26c477250cee7ce5d96d49c86c4e4dc
Former-commit-id: adb3d144c80d09ad5c1b616e8c4cad59d605364c
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox