Message identification for logging and communication

[cptshirty]

Hello, for my application I need to be able to log and eventually send messages through serial interface.
For this application it's important to be ablle to differentiate between the messages in case you write/read from a log file.
I am thinking of storing the messages like {class_id}{message_id}{the message struct}.

I am actually working on this on my fork of the project and i think it would be beneficial to merge upstream, since logging and communication is a part of a lot of projects, so I created this issue just so we can discuss this and there is a place to link the pull request if you agree that this is a good idea.