QPainter::isCullable(QBox3D) doesnt work for orthographic transforms

QPainter::isCullable(QBox3D) doesnt work for orthographic transforms - things can get culled when they should not due to the logic about the eye line.

It does make sense to use this for orthographic stuff - since you might have a 2D scene where stuff is off the screen.

Also it is convenient to use the QGLSceneNode to store materials and so on, and the draw function of this will automatically call isCullable (as it should).