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* CPack support for packaging.
* Stats, Top, and Expr no longer expose implementation details.
* API update: Attr::class_name is now Attr::type\_ and Top is now
Module.
* Document boost::optional<T> and improve its SWIG wrapper.
* Fix exception handling in Python wrapper.
* Python packaging improvements.
* Add enum support.
* Refactor parser and reuse integer parser for enum constants.
* Add template and arg support.
* Reorganize Python tests.
* Improve Visitor base implementation to visit all nodes.