Optimization for the duplicate paintop

[Cyrille Berger]

Hello,
I was working on optimizing the duplicate paintop, so with the help of 
Boudewijn I was able to cut the computation time by half.

But after that first optimization, 80% of the time is spend in bltSelection, 
and more specificaly in KisSelection::isTotallyUnselected(QRect r), and I was 
wondering if changing the following line :
QRect sr = selectedExactRect();

by
 QRect sr = selectedRect();

was acceptable ? (it considerably increase the speed of the duplicate tool, 
but might have drawback).

-- 
--- Cyrille Berger ---