Add sha512 w/hmac and other updates

Create C++ wrappers for additional C hash functions.
Three hash data types (long_hash, hash_digest, short_hash).
Update hash function names to deconflict with new.
Make bitcoin-specific hash names more explicit to avoid ambiguity.
Remove references to C hash functions in script processor.
Rationalize ecdsa wrapper getters and setters.
Fix gcc warnings from struct export attributes.
Disable cURL.