Adding NPVAR algorithm to the package

[AlxndrMlk]

Hi!

I'd like to propose to add NPVAR algorithm (Gao et al., 2020) to the package. I believe that this would facilitate benchmarking and further research in the field.

There is an existing R implementation provided by the authors.

What are your thoughts on this idea?

References

Gao, M., Ding, Y., Aragam, B. (2020). A polynomial-time algorithm for learning nonparametric causal graphs.