Implement the SubPackageMgr manager in BuildStore. This allows the
creation, querying and deletion of sub-packages.
Ensure that newly-added sub-packages caused a package-changed
notification message to be sent.
Modify ISubPackageMgr to use the trash/revive mechanism, rather than a
pure remove() approach. This is necessary to support the undo/redo
operations.
Implement a simple undo/redo operation for sub-packages.
Add listener notifications for SubPackageMgr.
Add the recordLocationChange() method to SubPackageUndoOp().
Use LocalSelectionTransfer() in the drag/drop mechanism to allow
dragging/dropping of UI elements between Eclipse views/editors.
Add the basic infrastructure for dragging packages onto a package
diagram and displaying, moving and deleting the pictograms.