Fixed Problem Difficulty, Author Rating, and Solver Rating Calculations

For a very long time, problem difficulty calculation was disabled on Toph. It and a few other things were disabled to make it easier to transition from Toph’s old database code to the current one.


This is a companion discussion topic for the original entry at https://blog.toph.co/changelog/2021-02-21-fixed-problem-difficulty-solver-author-ratings/