Take string arguments as const char *
This requires no changes in the actual code but makes tons of warnings in the clients go away when they pass a fixed compile time string.
This changes the public header file of the package, so it should not go into tdaq-09-04-00. I see there are patches being submitted to tdaq-09-04-00, so I would wait after things are stable, and then accept this MR and put it into the nightly build.