Mush

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

- Allow :class:`Plug` instances to be added directly using :meth:`Runner.add`
and friends.

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

- Add support for cloning depending on what label was used to add callables.

- Add :meth:`Runner.add_label` helper to just add a label at the end of the
runner.

- Document and flesh out :ref:`plugs`.

- Switch to full `Semantic Versioning`__.

__ http://semver.org/

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

- Stop catching :class:`TypeError` and turning it into a
:class:`~context.ContextError` when calling a :class:`Runner`. This turns out
to be massively unhelpful, especially when using Python 2.

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

- Add :class:`Plug` base class.

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

- Typo fixes in documentation.

- Indicate that Python 2.6 is no longer supported.

- Raise exceptions when arguments to :func:`requires` and :func:`returns` are
not either types or labels.

- Allow tuples are lists to be passed to :meth:`~modifier.Modifier.add`,
they will automatically be turned into a :func:`requires` or :func:`returns`.

- Better error messages when a requirement is not found in the
:class:`~context.Context`.

Thanks to Dani Fortunov for the documentation review.

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

- Re-write dropping all the heuristic callable ordering in favour of building
up defined sequences of callables with labelled insertion points.