BUG: Better solution for previous quick fix for DICOM exportables

Instead of setting the slicer application as parent for exportables, they are handled in the same block where they are read out, and the export dialog itself is set as parent, so the exportables are destroyed when the export dialog is closed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24277 3bd1e089-480b-0410-8dfb-8563597acbee