Configuraptor

Fix
* **alias:** Alias not always detected (e.g. in the case of postponed) ([`041f82c`](https://github.com/trialandsuccess/configuraptor/commit/041f82c6750ef96c0fadf2fe7e803b0c9814d11b))

Fix
* **alias:** Freeze and set slots so it can be used in a dataclass ([`a382269`](https://github.com/trialandsuccess/configuraptor/commit/a38226932c67281667c34171e0b01a6fb98925c7))

Fix
* If alias points to an Optional key and it is missing, don't throw an error but set the value to None ([`26ec586`](https://github.com/trialandsuccess/configuraptor/commit/26ec5869d24a53f081a844d63ad4fe93ec0ebeb5))

Fix
* Require a reasonable modern version of typeguard ([`1f1cbee`](https://github.com/trialandsuccess/configuraptor/commit/1f1cbee121e0fb9a7a9576ab3e22d1d03ede0c11))

Fix
* **alias:** Work with postpone and update ([`3dc2ada`](https://github.com/trialandsuccess/configuraptor/commit/3dc2ada06ee3a14ead7f4861aab518c644716568))

Feature
* **alias:** You can now define aliases for keys ([`5c72993`](https://github.com/trialandsuccess/configuraptor/commit/5c72993a47af3f955d8f9c4275c22b13736c7456))

Documentation
* **alias:** Added to example readme ([`72efe8f`](https://github.com/trialandsuccess/configuraptor/commit/72efe8fbe266c8903409036ac43adfcd6aa3112e))