NEW: functions to apply warping field to list of input images and merge them together
NEW: functions to apply warping field to list of input images and merge them together

Former-commit-id: 163b82f11932103fb8c9287a7f246a8f60ae0ba7
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox