BUG: 2816. Store SceneViews data in MRB file even if not present in the main scene for the case when the Scene Views are read from the scene file, the data pointer is NULL in this case.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22328 3bd1e089-480b-0410-8dfb-8563597acbee