First version of a Repaint Manager.
This allows each KoShape to have a repaint() method which will cause the
canvas to repaint it.
Design is a bit tricky due to the fact that each object can have more then
one canvas it works on; I have to work on that a little more but the idea
is already visible in the KoRepaintManager.h file

The bigest sacrifice I had to make is that KoShapeManager now has its own
list of the objects and a add/remove for the objects.
With the ShapeManager being a QObject anyway we can probably add some
slots to minimize the pain of a shadow administration.

Note that the repaint manager is currently not enabled as there are some
repainting bugs.
Edit FlakeCanvas::updateCanvas (in testapp/mainwindow.cpp) to enabled it.