add option to exit after make_help + fix exit code

- Defaults to previous behaviour, which was to exit.
- Fix the returned exit code: was 1, but should be 0, as asking for help
is not an error.

eo/src/ga/make_ga.h

@@ -93,7 +93,7 @@ void run_ea(eoAlgo<eoBit<eoMinimizingFitness> >& _ga, eoPop<eoBit<eoMinimizingFi
 // end of parameter input (+ .status + help)
 // that one is not templatized
 // Because of that, the source is in src/utils dir
-void make_help(eoParser & _parser);
+void make_help(eoParser & _parser, bool exit_after = true);
 
 /** @} */
 #endif