Enable debug logging

[ClemensLinnhoff]

I found some strange behavior with the loggingOn flag. OpenMCx seems to set loggingOn to True when calling the constructor of an FMU. But at some point the fmi2SetDebugLogging() function of the FMU is called with loggingOn set to False. So debug logging is always disabled for FMUs. Also, when setting the -v option.

I can hardcode the loggingOn flag to True in my FMU, and then the logging works. So OpenMCx is capable of receiving the log messages. They are also included in the mcx_all.log then. But the flag seems to be always set to False.

[ClemensLinnhoff]

@klausschuch any chance this could get fixed? Or am I understanding something wrong about the logging functionality?