BUG: fix memory leak of vtkCollection

Clear and delete the node collection to remove a memory leak
from the snapshot dialog.

Fixes Issue #3314



git-svn-id: http://svn.slicer.org/Slicer4/trunk@22324 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: 2816. Made data present in SceneViews to be stored in MRB file even if not present in the main scene.
 Restructured vtkMRMLApplicationLogic::SaveSceneToSlicerDataBundleDirectory() code, made it more modular.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22325 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Fixed build error in vtkMRMLApplicationLogic

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22326 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fixed gcc compile error. Removed redundant 'extension' argument

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22327 3bd1e089-480b-0410-8dfb-8563597acbee
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