title: create DateTime string for the beginning and the end of the day
body: <p>If I have a string of the following:</p>
  
  <pre><code>"2013-10-28"
  </code></pre>
  
  <p>and when I convert to a <code>DateTime</code> using the following function:</p>
  
  <pre><code>new \DateTime("2013-10-28");
  </code></pre>
  
  <p>it always gives me a <code>DateTime</code> with the time not set.   </p>
  
  <p>I want to have two <strong>DateTime :</strong>   </p>
  
  <ul>
  <li>one marking the beginning of the day, meaning at <strong>00:00:00</strong> </li>
  <li>another <code>DateTime</code> which is on the same date but at the end of the day <strong>23:59:59</strong>.</li>
  </ul>
  
  <p>How do I do this given the string above?</p>