Fix typos in umac documentation.
New aliases sha512_224_ctx and sha512_256_cxt, for the sha512_ctx struct tag.
Document additional sha512 variants.
ccm_decrypt_message: length argument is cleartext (dst) length

Also updated related functions.
Document that length arguments refer to the destination size.
CCM documentation.
Updated release plan.
Rename *_DATA_SIZE to *_BLOCK_SIZE.
New constants UMAC_MIN_NONCE_SIZE and UMAC_MAX_NONCE_SIZE.
Document additional GCM and UMAC constants.
Make HMAC and UMAC their own info nodes.
Minor whitespace fix.
Document EAX.
Update documentation for nettle_cipher_func.
Mention _DATA_SIZE to _BLOCK_SIZE rename.
Updated release plan.
Started on AEAD documentation.