duncanmmacleod/ciecplib: ciecplib 0.7.0

Major development release.

Backwards-incompatible changes:

• [https://github.com/duncanmmacleod/ciecplib/pull/113] Refactor X.509 handling to use cryptography

  Usage through the entry points or ciecplib.tool is unaffected, while all other functions now accept and return cryptography objects rather than M2Crypto or pyOpenSSL objects.

  pyOpenSSL is still used on old systems (RHEL 7/8) to accommodate very old versions of cryptography.

The full list of all changes related to this milestone can be seen at https://github.com/duncanmmacleod/ciecplib/pulls?q=milestone:0.7.0.