simple timer for javascript
##Installation:
include timer would append a function called createTimer
under window
namespace.
require the file and get createTimer function.
var createTimer = require(__dirname + '/timer');
##Usage:
var timer = window.createTimer();
timer.start();
// do some stuff to be measured here.
// ...
// ...
// stop the timer and get result
timer.stop();
console.log('total time elasped: ' + timer.getTimeInterval());