parse_newick is two pass, likely can be done in a single pass

[wasade]

Currently, the topology is parsed out first, then a second pass is made to pull out name and length information. The reason for this approach is that a name or length is, right now, associated with the opening parenthesis of a node within BP. This was an implementation decision which may make sense to revise. The disconnect with newick is that a name and/or length in newick is associated with the closing parenthesis or none at all in the case of a tip.

[wasade]

scikit-learn's cythonized Stack may be of use, likely wrap's c++'s STL