Openfhe

Fixes the compilation bug introduced by OpenFHE v1.1.2 (96)

* Adds EvalAdd for ciphertext and plaintext
* Updates the API documentation

For more details, see https://github.com/openfheorg/openfhe-python/issues?q=is%3Aissue+milestone%3A%22Release+0.8.2%22+is%3Aclosed

* Adds support for threshold (multiparty) FHE
* Adds support for serialization
* Fixes a bug in the CKKS bootstrapping example

For more details, see https://github.com/openfheorg/openfhe-python/issues?q=is%3Aissue+milestone%3A%22Release+0.8.1%22

Initial pre-release of the official Python OpenFHE wrapper.