Moved an include to the requisite .cc file.
Changed a bunch of RDB_DECLARE_ME_SERIALIZABLE macros to RDB_DECLARE_SERIALIZABLE.
Moved serialization of rdb_modification_report_t outside class.
Moved serialization functions outside of classes in profile.hpp.
Moved a bunch of protocol.hpp serialization declarations outside of class bodies.
Moved test_cluster_directory_t serialization declaration outside class body.  Removed an RSI -- made a Github issue for it.
Removed RSI comment.  The answer was no.  And meh.