Random Neighbor Louvain

[mneedham]

We want to implement Random Neighbor Louvain as per this paper - https://arxiv.org/abs/1503.01322

We can mostly reuse the code we have already, but make it configurable so that the user can choose which selection strategy is used. e.g. Have a config parameter such as:

communitySelection: "classic" or communitySelection: "random"

We can then add a 3rd strategy for pruning Louvain (http://www.ijcee.org/vol8/927-A023.pdf) at a later stage. Let's not do that one now though

[amyhodler]

Investigate Leiden - https://arxiv.org/abs/1810.08473