Custom painters for eye and dot

[rasmk]

It would be nice to have custom painters to generate fancy pics.

I imagine, QrImageView could accept functions like dataModluePainter and eyePainter besides dataModuleStyle and eyeStyle.

The functions would be responsible for rendering a single element (slingle eye, single dot).

For example, eyePainter would get position (top-left, top-right, bottom-left), size, x and y. dataModluePainter would get size, x, y and information about neighbouring dots (8 dots around), so that the shape could be different if it connects with other dots.