Iterators, selection and a few broken things for now

[Cyrille Berger]

Hello,
I am working on making the selection work with iterators, but to achieve this 
I have broken the quantum iterators (which was planed to disapear anyway), so 
functions which were relying on them would be broken (gradient, histogram and 
filling). And I have move the selections stuff from KisLayer to 
KisPaintDevice, I do think that everything related to painting should be put 
in KisPaintDevice and not in KisLayer.
-- 
--- Cyrille Berger ---