kis_tool_brush

[Patrick Julien]

> >
> > First with my implementation of the brush: I don't cache masks, which
> > makes painting too slow, and I don't do undo/redo yet, and no pressure
> > sensitivity and a host of unimplemented issues.

You also don't consider the spacing of the brush either.

> >
> > Second, there's still something quite wrong with the way we handle tools,
> > canvas updates and multiple views. Experiment with it; open an image,
> > open a new view, and start painting here, and there and everywhere...

Hmm, not really, it just seems to be missing a notify somewhere.  In any case, 
I hate the way we have to notify right now, there just way too many steps.  
The document should just connect to the update signal of KisImage, and from 
there, notify any view, period, nothing else required.