New online stats package

[PabloRuizCuevas]

I created this small package:

https://github.com/PabloRuizCuevas/onstats

Is similar to river stats, but focused in simplicity using only generators instead of classes. Is more a experimental project than anything else but I thought someone else may find it also interesting.

[MaxHalford]

Sure, can you make a pull request to add it?