* Full Python 3 support.
* Immutable object implemented.
* Bug fixes in PVector.__repr__() and PMap.__hash__() and index check of PVector.
* Repr changed to be fully cut and paste compatible
* Changed assoc() -> set(), assoc_in() -> set_in(), massoc() -> mset().
Sorry for the API breaking change but I think those names are more pythonic.
* Improved documentation.