Intervals

^^^^^^^^^^^^^^^^^^

- Removed interval constructor string parsing
- Added new class method from_string

^^^^^^^^^^^^^^^^^^

- Drop python 2.6 support

^^^^^^^^^^^^^^^^^^

- Made intervals hashable
- Added CharacterInterval class

^^^^^^^^^^^^^^^^^^

- Fixed interval datetime type guessing
- Fixed code examples in docs
- Fixed IntInterval step rounding
- Added better test suite (now docs are tested also)

^^^^^^^^^^^^^^^^^^

- Fixed setup.py packages

^^^^^^^^^^^^^^^^^^

- Added ``__bool__`` implementation for all interval types
- Added ``__int__`` support for ``IntInterval``