incremental/non incremental painting

[Boudewijn Rempt]

I've moved the option for choosing between incremental and non-incremental 
painting to the paintop options -- which means that paintops that don't work 
with this distinction can indicate so. The refactoring is not complete: I'm 
beginning to believe that painting mode should be another plugin category 
(since there are more fun things possible than just buildup and wash (which 
are the new user-visibile names for these modes), for instance fringed edges 
(the photoshop watercolor mode) or fractal edges -- but that's for after 2.0.
Plus, this option right now only works when painting on layers, not on masks.

The KisPaintopSettings::paintIncremental() function returns true by default, 
which means that by default paintops will paint directly on the layer's paint 
device; if you want your paintop to offer a choice, add the 
libpaintop/kis_paint_action_type_option.h option to your paintop option 
widget. See the way it's done in the brushop.

-- 
Boudewijn Rempt | http://www.valdyas.org