A Newick parser for Python, supporting internal node labels

I just pushed a fork of Thomas Mailund's nice Newick parser for Python to bitbucket. I added support for labeled internal nodes, but probably partially broke support for bootstrap values.

>>> from newick import parse_tree
>>> t = parse_tree("((Human,Chimp)Primate,(Mouse,Rat)Rodent)Supraprimates;")
>>> print t
(('Human', 'Chimp')Primate, ('Mouse', 'Rat')Rodent)Supraprimates
>>> print t.identifier
Supraprimates