Add a new feature to Shapes.
The KoShape::shapeChanged virtual hook has always been called when one of the properties of a shape changed; I expanded that by making it also get called when another shape is changed in the bounding rect of the shape to allow a shape to update itself if thats needed.

Note that I added a collisionDetection() boolean so there is little impact on performance for those that don't want it.

This effectively finishes the runAround of KWord to make sure layouting is changed when a shape is moved above it.