ENH: separate scene views with a line

Request from Ron, adding in a horizontal line between
scene views.

Issue #1299



git-svn-id: http://svn.slicer.org/Slicer4/trunk@23221 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix crash with vtkMRMLSelectionNode and vtkSlicerUnitsLogic

Since r23192, the GetUnitNodes() can return empty nodes.
This triggered asserts in vtkSlicerUnitsLogic.
vtkSlicerUnitLogic is only interested in unit quantities and IDs.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23222 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: #3694 check for valid image data before running pipeline

Since the display node is observing the image data directly it
may receive Modified events on image data that is not yet
completely constructed, in particular, during a DeepCopy, the scalar
fields may not yet have been copied when a ModifiedEvent is triggered
by one of the Set methods.

This change prevents a spurious vtkErrorMessage from being generated,
and so it allows the EMSegment test to pass.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23223 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Update qMRMLSliderWidget single step when range changes

The single step can depend on the range of the slider, update it when
needed.

Issues #3657, #3700
$ git shortlog 3aaa591..daaf705 --no-merges
Julien Finet (1):
      Virtualize ctkRangeWidget and ctkSliderWidget public API

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23224 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Update copy color icon

User feedback on the customisation of color tables suggested that
a more clear icon be used for the copy to edit functionality.

Issue #3573


git-svn-id: http://svn.slicer.org/Slicer4/trunk@23225 3bd1e089-480b-0410-8dfb-8563597acbee