Add functions for logging and enable levels of log

[Ralph Hempel]

From time to time, we have all used $(info ) $(warning ) and $(error ) to help us debug makefiles, but we have also longed for the ability to turn logging on and off at specific levels, such as trace, debug, info, warn, and error.

Would you be interested/able to implement this for the gmsl?

I am currently working on a simplified build framework for embedded systems using make - where developers can deal with lists of files and libraries and leave the complex make to a framework I call adapatabuild.

https://github.com/rhempel/adaptabuild-example
https://github.com/rhempel/adaptabuild

I am looking at gmsl for inclusion (with attribution) in adaptabuild if some of the functions are helpful

Bonus marks for having a nice test suite by the way!

[Ralph Hempel]

Oh wait, I can see you have something like this already in your function tracing ... let me chew on this a bit to see what I come up with for adaptabuild

[John Graham-Cumming]

Wouldn't be crazy to have adaptable logging. As long as it wasn't horribly complex. The tracing function is there really for debugging GMSL itself. I'd be interested to see what you suggest.