Record

----------------

- Set `__allow_access_to_unprotected_subobjects__` on the Record class.

- Remove the C extension.

----------------

- Use `ExtensionClass.Base.__new__`.

- Add support for Python 3.6, drop support for Python 3.3.

----------------

- Add support for Python 3.4 and 3.5.

- Drop support for Python 2.6 and 3.2.

----------------

- Add support for Python 3.2, 3.3 and PyPy using the Python reference
implementation.

- Add support for `__contains__`.

- Provide an Python reference implementation using `__slots__`.

- Rewrite tests as unit tests.

-------------------

- Released as separate package.