BUG: Fix "No LookupTable" error in qMRMLSliceWidget test

Full name of the test is: qMRMLSliceWidgetEventTranslatorPlayerTest1

The following error was reported:

//----------------------
ERROR: In /path/to/VTK/Imaging/vtkImageMapToColors.cxx, line 153
vtkImageMapToColors (0x268f190): RequestInformation: No LookupTable was set but number of components in input doesn't match OutputFormat, therefore input can't be passed through!

ERROR: In /path/to/VTK/Imaging/vtkImageExtractComponents.cxx, line 239
vtkImageExtractComponents (0x26947e0): Execute: Component 1 is not in input.

ERROR: In /path/to/VTK/Imaging/vtkImageExtractComponents.cxx, line 239
vtkImageExtractComponents (0x26947e0): Execute: Component 1 is not in input.
//----------------------

It is fixed by adding colorNodeRef attribute to VolumeDisplay element.

Also documented in the FAQ: http://wiki.slicer.org/slicerWiki/index.php?title=Documentation/Nightly/Developers/FAQ#Developer_FAQ:_MRML

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22654 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix missing (Interaction|Selection)Node in qMRMLSliceWidget test

Full name of the test is: qMRMLSliceWidgetEventTranslatorPlayerTest1

The following warning was reported:
//-----------
Warning: In /path/to/Slicer/Libs/MRML/DisplayableManager/vtkMRMLAbstractDisplayableManager.cxx, line 817
vtkMRMLVolumeGlyphSliceDisplayableManager (0x1548450): SetAndObserveMRMLDisplayableNode - MRMLScene does NOT contain any InteractionNode

Warning: In /path/to/Slicer/Libs/MRML/DisplayableManager/vtkMRMLAbstractDisplayableManager.cxx, line 583
vtkMRMLVolumeGlyphSliceDisplayableManager (0x1548450): CreateIfPossible - MRMLScene does NOT contain any InteractionNode

Warning: In /path/to/Slicer/Libs/MRML/DisplayableManager/vtkMRMLAbstractDisplayableManager.cxx, line 591
vtkMRMLVolumeGlyphSliceDisplayableManager (0x1548450): CreateIfPossible - MRMLScene does NOT contain any SelectionNode
//-----------

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22655 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Simplify logic in (Start|End)SliceNodeInteraction method

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22656 3bd1e089-480b-0410-8dfb-8563597acbee