Move affine/__init__.py to affine.py

[mwtoews]

This is an idea to move to a simpler one-module project design.

[sgillies]

@mwtoews I'm all for this. Let's do it after #111.

[mwtoews]

With these changes, the sdist contains:

affine-3.0.dev0/
├── affine.py
├── AUTHORS.txt
├── CHANGES.txt
├── docs
│   ├── make.bat
│   ├── Makefile
│   ├── requirements.txt
│   └── src
│       ├── conf.py
│       ├── index.rst
│       └── _static
├── LICENSE.txt
├── PKG-INFO
├── pyproject.toml
├── README.rst
└── tests
    ├── __init__.py
    ├── test_numpy.py
    ├── test_pickle.py
    ├── test_rotation.py
    ├── test_serialize.py
    └── test_transform.py

and the bdist wheel contents that would be installed into site-packages is:

.
├── affine-3.0.dev0.dist-info
│   ├── LICENSE.txt
│   ├── METADATA
│   ├── RECORD
│   └── WHEEL
└── affine.py

[sgillies]

Thanks @mwtoews !