Implement the remaining PKCS 3.0 functions, namely message based operations

[Jakuje]

The 3.0 defines message-based encryption/decryption/signature/verification, where at least the encryption and decryption might be useful.

Then there are dual-function operations, such as C_SignEncryptUpdate(), which might be relevant for FIPS as it does both signature+encryption at one step. I do not think we have a good use for these now, but it should be easy to combine them from existing operations.

[simo5]

Encryption/Decryption is done in #94