ArgParser::argPositional(char* arg)
{
    if (o.infilename == 0)
    {
        o.infilename = arg;
    }
    else if (o.outfilename == 0)
    {
        o.outfilename = arg;
    }
    else
    {
        usage(std::string("unknown argument ") + arg);
    }
}
ArgParser::argPositional(char* arg)
{
    if (o.infilename == 0)
    {
        o.infilename = arg;
    }
    else if (o.outfilename == 0)
    {
        o.outfilename = arg;
    }
    else
    {
        usage(std::string("unknown argument ") + arg);
    }
}