code: function register(gesture) {
      // add an enable gesture options if there is no given
      var options = gesture.defaults || {};
      if(options[gesture.name] === undefined) {
        options[gesture.name] = true;
      }
  
      // extend Hammer default options with the Hammer.gesture options
      Hammer.utils.extend(Hammer.defaults, options, true);
  
      // set its index
      gesture.index = gesture.index || 1000;
  
      // add Hammer.gesture to the list
      this.gestures.push(gesture);
  
      // sort the list by index
      this.gestures.sort(function(a, b) {
        if(a.index < b.index) { return -1; }
        if(a.index > b.index) { return 1; }
        return 0;
      });
  
      return this.gestures;
    }
docs: register new gesture
  @param   {Object}    gesture object, see gestures.js for documentation
  @returns {Array}     gestures