Need review and testing for 'zoom-pan-testing-kazakov' branch

[Friedrich W. H. Kossebau]

Forgot to mention this:

Am Sonntag, 9. September 2012, 17:12:56 schrieb Friedrich W. H. Kossebau:
> While Krita may not use documentOrigin() anymore, other parts/plugins of
> Calligra do, but will now fail if used with Krita. Not perfect. Would anyone
> agree with me that KisCanvas2::documentOrigin() needs a proper
> implementation again?

Especially not perfect because I was thinking about wiring up the rulers and 
the canvas directly, so not every application has to do the wiring itself, 
instead they would just pass the rulers a pointer to the canvas.

Krita breaking the API contract of KoCanvasBase would make this less useful.

Cheers
Friedrich