* Proposed new interface for AesSivEncrypt with number of ADs != 1.
* Implement AES SIV S2V computation with a number of ADs not equal to 1.
* Add Example A.1 from RFC5297 to AES SIV test vectors.
* Add tests for new AES SIV interface, and add test vectors for examples given in RFC5297.
* Include the nonce in count of maximum number of ADs.
* Addressing review comments.
* Addressing review comments: Use uppercase 'U' suffix on unsigned constant.
* Rename local variables named 'ad0' to 'ad', since the zero makes no sense, especially since in the RFC 5297 document they're actually counting the ADs from 1.
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