And suddenly Krita becomes an expensive image viewer instead of a capable
paint app.... Okay, let's break this down:

* All contact with tools now goes through a tool proxy (this turned
out to work best, in the end, out of the three approaches I tried. I
still think it's a pity I had to give up on the event filter approach,
that was way cool).
* I ported Kivio, Karbon and KWord to this system
* Krita now has a KoCanvasBase based canvas, but cannot yet handle flake
shapes, so don't click on the flake tools appearing in the toolbar.
* Krita now shows bits of layers that fall outside the image. This is cool.
* And the checks work.
* Fix a couple of krita file filters

TODO:

* Port Krita's tools
* Port the changes in kisdoc since my fork to kisdoc2
* Implement the tool-per-pointing-thingy
* Implement switching the tool based on what we thing the user is holding in
his hand.
* Implement zooming in Krita's canvas
* Port Krita's opengl canvas (should be easy, but I don't understand it)
* Re-add all the bits of gui, like dockers, filters, menu's and so on that
I chopped off