Yeah, Flacapella fetches images again.

And I also released RNOTags, which can embed/remove/replace pictures in MP3 files. You can even add multiple images, not just cover. It required quite much work to code the program, but I'm really happy with the result, it became the best ID3 tag editor I know :) It supports huge amount of frames and doesn't break any like most other editors or operating systems (try editing tags in Win10 and it f*cks everything it doesn't recognize).