> good raster photo editor with non-destructive editing capabilities

RawTherapee and DarkTable are both excellent (I prefer DarkTable), and in some cases have much better plugins and algorithms than Adobe has to offer in Lightroom or Photoshop. Which one works best mainly depends on your preferred UI set-up, but I'd say they're easily at Adobe's level:

http://darktable.org/

http://www.rawtherapee.com/