Both Actions and File Groups now have their (x, y) location stored in
the BuildStore database. Undo/redo also works for both of them.
Initial commit of support for a properties page for file groups. Allows
viewing of the content, adding new files, removing files, and reordering
the files.
The dialog box for adding files to a file group can now support multiple
selection, and also allows the selection of files (not just
directories).
Disable the package diagram's default context menu, which was far too
full and menu items that don't make sense.
Add listener support for FileGroupMgr changes.
PackageDiagramEditor now listens for changes to file groups, and redraws
when necessary.