Message Refactor: flattening message

[Boyu Yang]

• Remove redundant data and worthless functions.
  • Remove redundant enum MsgType and worthless functions (topic_to_string, id_to_key, de_cmd_id, display_cmd).
  • Remove cmd_id (submodules and topics) from communication messages.
• Make code more readable.
  • Change global functions for communication message to be class functions.
  • Use the same name for same thing in different places.
  • Standardize routing keys (Use the format as PublisherSubModule.ClassType).
• Reduce uncompress and deserialize.
  • Use routing keys to distribute messages and detect types.
  • Use fixed-length format messages for communication (Set or get Origin and OperateType directly).
  • Parse SignedProposal directly.
• Others.
  • Implement convert traits for protos.
  • Lots traits or functions will be generated automatically by a script.
  • Move all generated source codes into a separated directory.
  • Add some unit tests.