Use a Monav specific sub-logger for Monav stuff

Like this we can tell which messages come from Monav and which from Routino
(once Routino data generation is supported).
A rather big refactoring

* replace most getters by properties
* move relevant private variables to public properties
* make the code more PEP-8 like
* don't graph the exception if we are using the exception logging functionality and don't need the exception object
* general cleanup