BUG: copy the correct model display node, fixing a copy/paste error

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21619 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: add a new test for importing model heirarchies.

Test that when a model hierarchy is imported that changes to model ids
are reflected in the parent node ids of child hierarchies.



git-svn-id: http://svn.slicer.org/Slicer4/trunk@21620 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: add the ability to import multi level model hierarchies from CLIs

Added to support passing a template scene to the Model Maker 
that contains a multi level model hierarchy. 

TODO: decide the best practice when a hierarchy is imported twice (for 
example, running the model maker on the same label map more than once)
right now this will make a new hierarchy rather than over writing
the old one.



git-svn-id: http://svn.slicer.org/Slicer4/trunk@21621 3bd1e089-480b-0410-8dfb-8563597acbee