* Add cryptography backend for openssl_privatekey.
* Adding ECC support.
No support for X25519 and X449, since they don't support serialization.
* Improve finterprint calculation to work with Python 3.
* Add fingerprint check.
* Fix typo.
* Use separate curve option for elliptic curves, and use type 'ECC'.
* Using curve names as defined in IANA registry.
* Bump minimal supported cryptography version. Older versions might work as well, but I couldn't test them.
* Improve documentation.
