commandline argument --help and -V is printed to stdout, instead of stderr.
EXIT_FAILURE is returned at argc == 1. Just in case that qrencode is used in a shell script.
error message instead of usage(1,0).
"usage" function distinguishes between explicit call and a wrong usage.
explicit = stdout. else = stderr
Merge pull request #37 from d4ndo/master

commandline argument --help and -V is printed to stdout, instead of stde...