Savers must be const.
Saver must accept const argument. std::vector has size(), not length().
Remove unnecessary code.
Specific serialization-deserialization of key_chunks in key_message.
Encode and decode sized option type.
Wrap loggers into a namespace.

Now can use logger::debug(), logger::warning() etc to output to log.
Remove useless code from byte_array.
Mark small methods inline.
Add method to append data to byte_array.
Return byte_array data as an underlying vector type.
Remove vectorstream test.

In spite of boost.iostreams this code is useless.
Use boost.iostreams for vectorstream implementation.
Convert serialization test into a boost.unit_test.