code: function registerEvent(eventName, position, extra){
  
      currentSession.registerEvent(eventName, position, extra);
  
      // check size of events and handle making request
      _checkDataPairs();
      
  }
docs: Adds event to event list of media if it exists, else to its own events list
  @memberof DataManager
  @param {string} eventName name of the event
  @param {string} position 3D position associated with the event
  @param {object} extra extra information and filter key-value pairs in the event