* Add LLMD5::clone(unsigned char const*), the inverse of LLMD5::raw_digest.
* Add LLMD5::clone(std::string const&), the inverse of LLMD5::hex_digest.
* Add LLMD5::isFinalized(), returns true if the object is finalized.
* Turn all binary operators into inline friends in the class.
* Fix operator<< to take a LLMD5 const& instead of a LLMD5&.
These changes are needed for / used by AIMultiGrid.