Stepped-augustus

Added
- `flake8` and `pre-commit` as development dependencies.
- `_do_skip` and `_do_stop` methods for checking character predicates.
- `skip_chars` and `stop_chars` parameters for extending behaviour.
- Documentation for `SteppedAugustus` parameters.

Changed
- Fix docstring inconsistency between `SteppedAugustus` docstring and `README.md`
- Fix return type annotation for `SteppedAugustus._cipher`

Added
- `CHANGELOG.md`
- Repository URL in `pyproject.toml`.

Changed
- Refactor `SteppedAugustus._cipher` to a generalized, easy to modify, and lazy algorithm.
- Refactor `SteppedAugustus._cipher` to include tabs and newlines.
- Refactor `SteppedAugustus.right_cipher` and `SteppedAugustus.left_cipher` in accordance to
the change in `SteppedAugustus._cipher`.
- Refactor documentation.
- Fix typo in `README.md`.
- Fix rouge character in `README.md`.
- Fix formatting of Suetonius' quote in `README.md`.

Added
- `SteppedAugustus` class interface that implements the functionality from the original
proof of concept through the `_cipher` method, and the `right_cipher` and `left_cipher`
properties.
- Availability through PyPI.

Changed
- Use the `SteppedAugustus` interface for the command-line application.

Removed
- Initial proof of concept module.

Added
- Initial proof of concept module.
- Initial command-line application.