BUG: enable reading of GE DWI trace multi-volumes, which was not possible to properly read using any existing functionality of Slicer


git-svn-id: http://svn.slicer.org/Slicer4/trunk@22161 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: #2326 remove storage nodes for sample data downloads

Since the download is in a temp directory, make sure the user
is prompted to save when saving the scene.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22162 3bd1e089-480b-0410-8dfb-8563597acbee