BUG: update management of crop volume parameters node

The module was holding a pointer to the parameter node that could get out of
date on scene changes and cause crashes. Switch to using a mrml node combo
box to manage the parameters node.
Adjusted the UI file to allow the generic module widget test to pass.
Update the widget more fully on enter and scene changes. Select a newly added
input volume or ROI if none already selected. When picking a new input volume,
or switching ot a new parameter set one, set it to be active in the slice viewers.
Update the parameters node constructor, destructor, read/write xml, copy and print
for missing calls. Make sure that the GUI updates the parameters node (was missing
the input volume and ROI node IDs).
Added a scene close to the self test, and add the CMake command to make it show
up as a self test in the GUI.
Added error checking, took out debugging print outs.

Tested against issues: 0003947 0001764 0003313

Issue 0003947

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23973 3bd1e089-480b-0410-8dfb-8563597acbee