Update charlstest to return EXIT_SUCCESS/FAILURE
Update charlstest to return EXIT_SUCCESS/FAILURE

To support that charlstest can be used reliable in scripts and on
the command line the return values of the application have been
updated to use the default conventions of UNIX and Windows.
This resolves #19.

cureos/charls,team-charls/charls,team-charls/charls,cureos/charls,cureos/charls