In get_raw_secret_value()

`os.path.splitext(filename)[1]` includes the '.'

The current heuristic will never return True

Start capitalized and after 2 spaces when on the same line as code

- Add `pyahocorasick` as an optional dependency

See issue #240 for more information.

By .lower()ing when creating and retrieving

- 🐍 Refactor hadouken code
- 🐍 Remove high_entropy_strings.py from the uncovered files list in tox

- Change `is_secret` string names to `(true|false)-positives` (Negative meaning false-positive was confusing.)
- Replace list of secrets with {filename: {plaintext: line:}}
- Replace top-level `results` key with `plugins` since we have a results key already

And normalize main_test.py comments

When following a symlink, we just subtracted the `cwd` from the path.
This caused us to scan non-existant files.