How to set verbosity of the LOG messages?

Hi, 

Mars provides a logging mechanism, defined [here](https://github.com/rock-simulation/mars/blob/master/interfaces/src/Logging.hpp).

Nevertheless, I don't see any documentation on how to change the verbosity level. When I run a mars program all log messages are displayed on the terminal. Is there a way to set a Logging level so only messages above that level are displayed?

