title: Ebay API ISO 8601 duration format to timestamp
body: <p>Ebay API provides me time in ISO 8601. </p>
  
  <p>For example, it gives me item time left: <strong>P0DT0H1M4S</strong>
  Here is how this time is formatted: <a href="https://developer.ebay.com/DevZone/finding/CallRef/types/simpleTypes.html#duration" rel="nofollow">ebay duration</a></p>
  
  <p>I want to convert this time to simple Y-m-d H:i:s format. 
  So far I've tried <code>date("Y-m-d", strtotime("P0DT0H1M4S"));</code> but it does not work.</p>