Recommend New Features: average GPA ranking

[Robert-Jia00129]

It would be helpful to be able to sort classes based on average GPA/difficulty. It would also be helpful to filter classes based on tags. Saves a lot of time when trying to find appropriate lib ed classes.

[samyok]

Hey Robert! I think that these are great ideas, you (or anyone else) can feel free to make changes and open a PR :)