Tennis player Elo modelling

I'm a big believer in Elo ratings as an approach for modelling fitness (having used them in my dissertation and other projects I can't talk about). I've been working on an pretty simple dashboard for exploring tennis players Elo ratings based on this fantastic resource](https://tennisabstract.com/reports/atp_elo_ratings.html).

I'll be working on prediction simulation next. Let me know if you want access!