Please add CLI option for threading about plater HOT 1 OPEN

void help()
{
    cerr << "Plater v1.0 (https://github.com/RobotsWar/Plater)" << endl;
    cerr << "Usage: plater [options] plater.conf" << endl;
    cerr << "(Use - to read from stdin)" << endl;
    cerr << endl;
    cerr << "-h: Display this help" << endl;
    cerr << "-v: Verbose mode" << endl;
    cerr << "The size of the bed plate (topview, 2D):" << endl;
    cerr << "  -W width: Setting the plate width (default: 150mm)" << endl;
    cerr << "  -H height: Setting the plate height (default: 150mm)" << endl;
    cerr << "-D diameter: Set the plate diameter, in mm. If set, this will put the plate in circular mode" << endl;
    cerr << "-j precision: Sets the precision (in mm, default: 0.5)" << endl;
    cerr << "-s spacing: Change the spacing between parts (in mm, default: 1.5)" << endl;
    cerr << "-d delta: Sets the interval of place grid (in mm, default: 1.5)" << endl;
    cerr << "-r rotation: Sets the interval of rotation (in °, default: 90)" << endl;
    cerr << "-S: Trying multiple sort possibilities" << endl;
    cerr << "-R random: Sets the number of random (shuffled parts) iterations (only with -S)" << endl;
    cerr << "-o pattern: output file pattern (default: plate_%03d)" << endl;
    cerr << "-p: will output ppm of the plates" << endl;
    cerr << "-t threads: sets the number of threads (default 1)" << endl;
    cerr << "-c: enables the output of plates.csv containing plates infos" << endl;
    exit(EXIT_FAILURE);
}