Viaduc

- Add msg argument to `done()`

- Improve long description
- Improve CLI help
- Add done and callback methods
- Improve image-viewer
- Rename `_print`
- Update README
- Add editor-example to README
- Add editor-example.gif

Update project description

- Remove type annotations from some files
- Correct shebang

- Add import to __init__.py

Initial release