Relax objectlib's requirements: it can be displayed not only on top of a DistortedScreen, but any DistortedFramebuffer.
progress with off-center objects.
1) introduce possibility to move objects, i.e. display them not in the middle of the screen (not fully functional yet)2) do away with unneeded any more interface 'EffectController' - since ObjectPreRender is the only implementation now.
Simplifications
Move yet more code to objectlib.