Thanks to the awesome rsn8887 I can finally wipe this from my wishlist
He merged the scalers from MartySheppard's repository into the current branch and did the merge.Some quick'n'dirty pictures:
https://www.dropbox.com/sh/0p9zmcoa4dfh ... waYka?dl=0
Use this setup-script:
https://www.dropbox.com/s/s5nn53pe8x2qt ... vm.sh?dl=1
copy to: /home/pi/RetroPie-Setup/scriptmodules/emulators/scummvm.sh
Here's rsn8887's branch with the merged scalers from marty:
https://github.com/rsn8887/scummvm/tree/scanlines