STYLE: Reorder CLI description XML elements

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21903 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Add drag&drop support for registered IO dialogs.

To support drag&drop, a qSlicerFileDialog derived class should reimplement:
 * qSlicerFileDialog::dragEnterEvent()
 * qSlicerFileDialog::dropEvent()

By default, qSlicerDataDialog supports drag&drop.

Issue #3081

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21904 3bd1e089-480b-0410-8dfb-8563597acbee