Other kinds of centralities measurements for selecting seeds

[aoliveram]

Review other centrality measurements that could outperform 'degree centrality' in threshold/complex contagion.

Currently, the code only allows selecting nodes according to degree centrality. However, it would be great if the function rdiffnet could accommodate other types of centralities, especially the complex centrality introduced by (Guilbeault and Centola), which should outperform classic centrality measures.