edit comments and docstrings, rm a redundant import
merge Transitions.add_labeled_adj into .add_adj

and update it to Transitions.add, so now it accepts keyword arguments.
override networkx.MultiDiGraph.add_edges_from in LabeledDiGraph

to avoid new keys being generated and so identify edges with their annotations.
wrap LabeledDigraph.add_edges_from in Transitions_add_from
rewrite Transitions.find
change default arg value for States.find
misc small changes