title: stopping and resuming tutorial using intro.js
body: <p>I'd like to guide user through a step by step tutorial on my website. The tutorial will stop after each step, and after the user provided an input, I would like to resume the tutorial.  I start the tutorial by invoking</p>
  <pre><code>introJs().setOptions({
        steps: [{
          title: 'Welcome {{ user_data }} ',
          intro: &quot;I shall guide you!&quot;,
          step: 0
        },
        {
          title: 'Select a Word',
          element: document.querySelector('#word'),
          intro: &quot;First, select a word!&quot; ,
          step: 1
        }
        ]
      }).start();
  </code></pre>
  <p>after user select a word, i have a onChange() method that adds another piece of tutorial by:</p>
  <pre><code>introJs().addStep({element: document.querySelector('#step2'),
                         Title: &quot;Select this&quot;,
                         intro: &quot;Select this&quot;,
                         step: 2
                        });
  introJs().goToStep(2).start();
  </code></pre>
  <p>This doesn't seem to resume the tutorial.
  What am I missing? is this possible at all?</p>