Numpoly

===========================

ADDED:
* First iteration Sphinx docs.
* Increased testing coverage.
* Numpy function additions: `atleast_1d`, `atleast_2d`, `atleast_3d`,
`ceil`, `floor`, `dstack`, `hstack`, `vstack`.

CHANGED:
* CircleCI cleanup: limited py27 and full py37 testing only.

===========================

ADDED:
* Add align_dtype to alignment process.

CHANGED:
* Recast dtype support in `ndpoly.__call__` when input is other format than
internal one.

===========================

ADDED:
* Numpy functions: `prod`, `moveaxis`.

CHANGED:
* Move testing dispatching to `conftest.py`.
* Testing polish.

===========================

ADDED:
* Testing of alignment.
* Numpy function additions: `allclose`, `isclose`, `isfinite`, `mean`.

CHANGED:
* Split testing suite into py2 and py3
(as py3 supports full dispatching, and py2 does not).

FIXED:
* Variable name typo fixes.

==========================

ADDED:
* Linting to CircleCI checks.
* `simple_dispatch` function to unify the backend for the most simplest
numpy functions.
* Support for numpy reduce and accumulate mappings.
* `ndpoly` methods: `from_attributes`,
`round` (likely needed because of numpy bug).
* Numpy functions: `logical_and`, `rind`, `square`.

CHANGED:
* Some code clean-up of alignment.
* Refactor constructions functions.
* Renamings: `ndpoly.{_exponents -> keys}`,
`ndpoly.{_indeterminants -> names}`,
`numpy.{clean_polynomial_attributes -> clean_attributes}`

==========================

ADDED:
* Polynomial functions: `aspolynomial`.
* Numpy functions: `around`, `common_type`, `inner`, `logical_or`.

CHANGED:
* Functions for mapping between `Tuple[int, ...]` and `str` for dealing with
exponents, instead of using exposed maps.
* Split array functions into one-file-per-function.