Autocrop

Changes

- The `initial-setup` step in Makefile now also installs development packages.
- The `black` formatting package now gets installed with `requirements-dev.txt`

Deprecations

- Deprecate Python 3.6

Changes

- Modify the `opencv-python` dependency over to `opencv-python-headless`, which doesn't have all the GUI baggage. Easier to download and package.

Documentation

- Created the `examples` directory and moved the example notebook to it.

Deprecations

- Deprecate Python 3.5
- Deprecate OpenCV 3

API Additions

- User can now specify what file extension to save cropped files at the CLI

Security

- Update Pillow dependency in order to limit possible security issues

Other changes

- Updates to the developer setup tools and documentation
- Updates to the example notebook

Added

- CLI now copies file by default

Added

- Cropper class now available from Python API.
- Local multi-version testing for Python now available with `tox`.
- Extra regressions tests to defend against image warp and cropping outside the regions of interest.
- Support for Python 3.8

Bugfixes

- Specify encoding in `setup.py`, which was causing some errors on Windows.

Deprecated

- Support for padding argument — this is now solely handled by the `face_percent` parameter, and enforces the aspect ratio between `width` and `height`.
- Support for Python 2.7

Changes

* Autocrop now prints the filename of images where face detection failed
* Internal refactoring and more tests