REF: added message "no smoothing" if -size 0 flag to avoid confusion (see Allan email)
REF: added message "no smoothing" if -size 0 flag to avoid confusion (see Allan email)

Former-commit-id: 7e7ad3c0b8c32d6cf9a7f9d0789e3e7a195ec8c6 [formerly 734e0b7a61dcf1ffd5886c742580cff47285db33]
Former-commit-id: eef65cf3410d67aa674614d89f984a1fc951c6f7
Former-commit-id: 134881f3e4c5575132b82ba0640957bceaece1b1
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox