OPT: register_to_template: added smoothing again
OPT: register_to_template: added smoothing again

Former-commit-id: 2a1bb1c87a68dc8257d5ba3f67a7c7831c72e6d6
Former-commit-id: 4636690601bc8d5f10d76ce35f21458dd3f980c9
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox