Merge pull request #5082

5f4bcf6 boost: drop boost dependency in version.cpp. (Cory Fields)
352058e boost: drop boost dependency in utilstrencodings.cpp (Cory Fields)
e1c9467 boost: drop boost dependency in core.cpp (Cory Fields)
e405aa4 boost: remove CPrivKey dependency from CECKey (Cory Fields)
5295506 boost: drop dependency on tuple in serialization (Cory Fields)
1d9b86d boost: drop dependency on is_fundamental in serialization (Cory Fields)