Widget remains problematic as it uses QGraphicsItem API, but it needs to be subclassed by items that are already QGraphicsItems. ugh.
svn path=/trunk/KDE/kdebase/workspace/plasma/lib/; revision=668083
* make DataEngine take a QObject in the connect, making DataVisualization somewhere superfluous. unless it ends up doing something useful soon, DataVisualization as a class will be going away.
svn path=/trunk/KDE/kdebase/workspace/plasma/lib/; revision=667167
* move DataSource::Data to DataEngine::Data; this means consumers of DataEngine have no need to know about DataSource as a class
svn path=/trunk/KDE/kdebase/workspace/plasma/lib/; revision=666756