analysing and comparing trees.

Analyse iterates over the directories of trees and compares reference tree with all the mutations. It compares a mutation both by direct comparison and by generating a filtered version first. The actual comparison is done by cmp_tree.py

cmp_tree compares two trees, one given through stdin and one as an argument and returns the difference between them as the program return code. The default comparison method uses the module dendropy's symmetric_difference. There is also a compare_exact that returns 0 for equal and 1 for non-equal.