code: function(src, onload, onerror) {
  		this.id = -1;
  		this._src = '';
  		this.complete = false;
  		this.onload = onload;
  		this.onerror = onerror;
  		if (src) {
  			this.load(src);
  		}
  	}
docs: ARCameraParam is used for loading AR camera parameters for use with ARController.
  Use by passing in an URL and a callback function.
  
  var camera = new ARCameraParam('Data/camera_para.dat', function() {
  console.log('loaded camera', this.id);
  },
  function(err) {
  console.log('failed to load camera', err);
  });
  
  @exports ARCameraParam
  @constructor
  
  @param {string} src URL to load camera parameters from.
  @param {string} onload Onload callback to be called on successful parameter loading.
  @param {string} onerror Error callback to called when things don't work out.