* implement the DragAndDropHelper as singleton derived from QObject, so that emitting...

* implement the DragAndDropHelper as singleton derived from QObject, so that emitting of signals is possible
* show an information message in the statusbar, if items are dragged into the same directory

TODO: although the signal seems to get connected correctly, the slot DolphinMainWindow::showInformationMessage() is not invoked when the signal is emitted -> will debug this later, it is important that the new string is added before the message freeze

svn path=/trunk/KDE/kdebase/apps/; revision=881627