-------------
- Added :meth:`pratt.Grammar.enclosing`.
- Changed :class:`pratt.Grammar` by giving it's `__init__` method a default
implementation for the `handle_unexpected_token` argument. The new default
implementation raises :exc:`pratt.UnexpectedToken`.
- Added :exc:`pratt.PrattException`. At the moment it's not raised and only
subclassed by :exc:`pratt.UnexpectedToken`. It's primary reason for existance
is to serve as a base class for future exceptions.
- Added documentation.
- Added :meth:`pratt.Grammar.ternary`.