TODO: More clustering algorithms

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Except HCA, SocNetV should implement the following clustering algorithms to automate finding community structure:

• the Girvan-Newman algorithm, older one for small graphs mainly, see paper " Community structure in social and biological networks"
• the Clauset-Newman-Moore algorithm, see paper "Finding community structure in very large networks"
• the Wakita and Tsurumi algorithm, see paper “Finding Community Structure in Mega-scale Social Networks”