Features in Office
Added an opacity PaintOp option and increased the performance of the brush.
Two things were done to increase performance:
* avoid to use KisPainter::paintRect(...)
a temporary KisFixedPaintDevice filled with the needed color is now used instead
* avoid to recalculate the brush mask on every paintAt(...) call
now the mask is only recalculated if size or rotation has changed significantly
in comparision to the last mask used