Custom-inherit

- This release adds three new built-in styles, `numpy_with_merge`, `google_with_merge`, and `numpy_napoleon_with_merge`, which
permit users to concatenate the respective sections of a parent's and child's docstrings.
Also added is the ability to configure `DocInheritMeta` so that special methods will have their docstrings inherited as well.
([31](https://github.com/rsokl/custom_inherit/pull/31)). Big thanks to [Boubsi](https://github.com/Boubsi) for these nice features!

- This release does not contain any changes to the `custom-inherit` code base. Changes are made to some of the packaging files so that `custom-inherit` can be hosted on conda.

- Dropping support for Python 3.3
- Adding support for Python 3.8
- This will be the final version of `custom_inherit` to support Python 2.7
- Minor code refactoring (formatting with black & isort)

- Previously, the class docstring inherited only from the most immediate parent class that has a docstring. Now,
the "parent" docstring is accumulated by successively merging the accumulated string with the docstring of
the next-parent in the mro. This accumulated docstring is then merged with the docstring of the present class. This permits sensible class-docstring inheritance in cases of multiple inheritance.
- Minor code refactoring.

- Added compatibility with Python 3.3 & 3.4

- [Napoleon](http://sphinxcontrib-napoleon.readthedocs.io/en/latest/index.html#id1) docstring specifications for Google and NumPy docstring formats are supported as defaults ('google' and 'numpy_napoleon').
- [reST section-delimited](http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#sections) docstring inheritance is supported via the default style 'reST'.
- `custom_inherit` now has unit test coverage for the entire package (for Python 2.7, 3.5, 3.6).
- Import styles updated for compatibility with Jython 2.7.
- Improved documentation.