Pynrw

What's Changed
- Implemented database classes by realshouzy in https://github.com/realshouzy/pynrw/pull/3
- Add reverse tree traversal by introducing the `reverse` boolean keyword argument in 0887f3e
- Marked `reverse_inorder` as deprecated in 792c0a4
- Further internal adjustments

**Full Changelog**: https://github.com/realshouzy/pynrw/compare/v1.2.0...v1.3.0

- Implement `__str__` and `__repr__` for all datastructures
- Simplify project structure by consolidating stubs into their respective `__init__.pyi`

**Full Changelog**: https://github.com/realshouzy/pynrw/compare/v1.1.1...v1.2.0

- Fixed `AttributeError` when calling `str` with empty `List`, `Stack` or `Queue`

**Full Changelog**: https://github.com/realshouzy/pynrw/compare/v1.1.0...v1.1.1

- implemented `__str__` for `List`, `Stack` and `Queue`
- further minor internal adjustments

**Full Changelog**: https://github.com/realshouzy/pynrw/compare/v1.0.0...v1.1.0

First major release.

**Full Changelog**: https://github.com/realshouzy/pynrw/commits/v1.0.0