Jan Kölling

@dotob Hey Sebastian, I agree that this might be useful, but this PR contains all of our changes from the German translation and not just the images without the text....

I'd be happy to help with the translation. (I did the German translation for Nicky's "Game of trust" btw.)

@stellingsimon I've found "Intervall-Lernen" for "spaced repetition" in [the translation of the Anki documentation](http://www.dennisproksch.de/anki#welchen-algorithmus-f%C3%BCr-intervall-lernen-verwendet-anki).

@stellingsimon I've added my first pull request to your fork and will try to move as much of the German specific discussion as possible over there.