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.
function(src, onload, onerror) {
		this.id = -1;
		this._src = '';
		this.complete = false;
		this.onload = onload;
		this.onerror = onerror;
		if (src) {
			this.load(src);
		}
	}