[Feature request] Implement FSRS because SM2 is flawed

[v-Nyo]

FSRS: https://github.com/open-spaced-repetition

Detailed comparison to SM2 (Anki): https://www.youtube.com/watch?v=OqRLqVRyIzc

I also experience that SM2 shows cards far too often in the beginning and is far to optimistic after a while.

An Implementation of FSRS for Emacs would be awesome!

EDIT: Just noticed in you activity overview that you already had some discussions about FSRS not sure if you are interested in implementing it in org-fc.