title: php: setting a timezone by UTC offset
body: <p>Using javascript I know that my users timezone is UTC +3. </p>
  
  <p>Now I want to create DateTime object with this knowledge:</p>
  
  <pre><code>$usersNow = new DateTime('now', new DateTimeZone("+3"));
  </code></pre>
  
  <p>I receive as a respsonse:</p>
  
  <pre><code>'Unknown or bad timezone (+2)'
  </code></pre>
  
  <p>What am I doing wrong? How can I fix?</p>