Feature: Assortativity #158

Is your feature request related to a problem? Please describe.
Observing https://github.com/ascanioalfredoa/OverlapCommAssortativity and seeing that CDLib does not include this measure, it is good to note that this repo exists.

Describe the solution you'd like
The Repo is in R, and the citation is https://www.sciencedirect.com/science/article/pii/S0003347215004480?via%3Dihub

Describe alternatives you've considered