OPT: register_to_template: changed smoothing from 3mm to 1.5mm
OPT: register_to_template: changed smoothing from 3mm to 1.5mm

Former-commit-id: 557e196886cf137c4321912807857a754a807101
Former-commit-id: 839b8408c3d91f265f2b9a5d788cf65f705c4cd0
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox