Fixes for compilation warnings
In addition to the changes proposed here, I have a question about a format line I find suspicious. I did not change it as part of this merge request, because there is no syntax error as such, but it might be a typo:
https://gitlab.cern.ch/ellert/HepMC3/-/blob/master/src/WriterAsciiHepMC2.cc#L139
The format string on this line says %ii with two i's. The second i is not part of the format option and will be printed. Is this 'i' part of the expected output here, or is it a typo.
$ printf '%ii\n' 123
123iEdited by Mattias Ellert