boost: moveonly: create eccryptoverify.h|cpp and move helper functions there

Eventually (after 0.10) these files will hold the logic for crypto
verification routines, and CKey/CPubKey will call into them.
boost: moveonly: move BIP32Hash to hash.h
boost: moveonly: split CPubKey and friends to new files
Merge pull request #5162

d2e74c5 boost: moveonly: split CPubKey and friends to new files (Cory Fields)
78c228c boost: moveonly: move BIP32Hash to hash.h (Cory Fields)
900078a boost: moveonly: create eccryptoverify.h|cpp and move helper functions there (Cory Fields)