COMP: Build 'DICOMDiffusionVolumePlugin' only if diffusion support is enabled

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22863 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Add convenience function 'slicer.util.getFirstNodeByClassAndName'

This is required because the function vtkMRMLScene::GetFirstNode
is not wrapped. Indeed, his third parameter is a pointer to
an integer.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22864 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Ensure label can be changed if it was been toggled.

Following commit r22862 fixing issue #3576 to ensure label is restored
after switching effect, the label couldn't be changed after it being
toggled.

This commit now ensures that label is reset when eraseLabel has been
enabled and effect is switched.

See #3576

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22865 3bd1e089-480b-0410-8dfb-8563597acbee