Stellapy

- Fix a bug which caused stella to sleep for a long duration if an error occured in the firefox browser

- Windows support
- Gitignore support
- Configuration is now project specific, and in YAML
- Browser compatibility has been fixed since helium uses webdriver manager now
- Migrate to pyproject.toml from setup.py, requirements.txt
- `rb` input to only refresh browser window
- Remove config command
- Executor is more capable - executing multiple commands
- Fix minor bugs

- Initial release