#27 Also be able to load certificates from engines

[Martin Peylo]

Certificates can be accessible by means of PKCS#11 - if the security token is changed, it is beneficial when the certificate comes along with the key.

This should be enabled in the CLI.

[David von Oheimb]

The OpenSSL engine interface only supports use of keys, but not their generation nor storing and retrieving certificates. PKCS#11 (and to some extent also PKCS#15) can indeed be used here.

For Windows, an interface to CNG (for accessing the Windows cert and key stores) would be nice.