Sciencedates

* improve test coverage and types tested

* functionalize tests
* improve test coverage
* setup.cfg <= setup.py
* RST=>md

Enable np.ndarray in/out for most functions.

Due to upcoming changes in Numpy deprecating timezone-aware handling by numpy.datetime64, and the numerous essential libraries which depend on Numpy,
we have defaulted to timezone-naive.

The .forceutc() function still allows coercing to UTC if desired, but this is **no longer** used internally as it used to be.

Also CI now uses `flake8` and `mypy` type checking. As usual, type checking helped uncover some corner cases.

allow datetime.date that comes into forceutc() to return unchanged.