* Returns a measure of the similarity ("average bootstrap similarity")
* between the topologies of phylogeny and evaluator_phylogeny: (sum of
* branches which divide phylogeny in a manner consitent with
* evaluator_phylogeny)/sum of branches in phylogeny. Therefore, this
* measure is 1.0 for indentical topologies and 0.0 for completely
* incompatible topologies.
* Returns a measure of the similarity ("average bootstrap similarity")
* between the topologies of phylogeny and evaluator_phylogeny: (sum of
* branches which divide phylogeny in a manner consitent with
* evaluator_phylogeny)/sum of branches in phylogeny. Therefore, this
* measure is 1.0 for indentical topologies and 0.0 for completely
* incompatible topologies.