Mrpython

* The walker now checks for a limiting attr on the Graphable interface. You can change the name of this attribute from its default of _dict_attrs . The reason it's private is because it's really meta data.

* Changed the walker to use explicit iterable types so as to avoid unexpected behavior with types that have an '__iter__' property but are not really iterable...

* Changed the way the recursive walker works. Got rid of the DictInterface . The implmentation for the interface is now up to the application developer. The fxn.to_dict(o, limit=()) and the fxn.walk(o, graph_max=None, graph_interface=None) functions provide the abstract functionality necessary to traverse and convert an arbitrary set of data structures / objects into a dictionary with full or limited recursion. The application developer merely specifies the graph_interface argument so that the walker knows when to treat a value as a graphable object. Otherwise, it just treats basic structures.

* List recursion bug-fix. Make the list walker subject to the same recursion level constraints as a regular dict interface...

* Added support for the recursion=True or recursion=n for the to_dict property. Specify True for unlimited traversal, specify a number for a max levels of recursion.
* Breaking Change: recursive=True no longer a parameter for to_dict

* Fixed recursion bug.