Added function on_release in CVPropseg to deal with manual/auto segmentation.
Added function on_release in CVPropseg to deal with manual/auto segmentation.


Former-commit-id: ff99c0509433c0fad46c07b0145a795984ae8a5d
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox