Logging of errors when instantiate is called with loggingOn = fmi3False

[klausschuch]

FMI 3.0 reference FMUs log error messages even if loggingOn==fmi3False is given to the instantiate function:
Corresponding code fragment in cosimulation.c:

        comp->logEvents            = loggingOn;
        comp->logErrors            = true; // always log errors

However, the FMI 3.0 standard says:

If loggingOn = fmi3False, then any logging is disabled and the logMessage callback function
must not be called by the FMU.

I personally prefer that FMUs always report log messages when errors occur and would even prefer to weaken the sentence in the standard but we should deal with this inconsistency.

[chrbertsch]

Torsten: I think that this is an ambiguity of the standard ... some other place we tell that errors should be reported.

Pierre: what are our rules for the callback? We should avoid having a NULL-pointer call. We could adjust the wording.

Klaus: if we change this, this would be a breaking change.

Pierre: I would for now live how it is defined.

Klaus: it is hard to find out which log category provides only errors.

Garron: As a user it would be nice if as a default the error would be printed.