title: error with unicode and simple xml
body: <p>I try to add a string to an XML object with Simple XML. </p>
  
  <p>Example (<a href="http://ideone.com/L4ztum" rel="nofollow">http://ideone.com/L4ztum</a>):</p>
  
  <pre><code> $str = "&lt;aoc&gt; САМОЛЕТОМ ТК Адамант,  г.Домодедово, мкр-н Востряково, Центральный просп. д.12&lt;/aoc&gt;";
  
  $movies = new SimpleXMLElement($str);
  </code></pre>
  
  <p>But it gives a warning:</p>
  
  <blockquote>
    <p>PHP Warning:  SimpleXMLElement::__construct(): Entity: line 1: parser error : PCDATA invalid Char value 2 in /home/nmo2E7/prog.php on line 5</p>
  </blockquote>
  
  <p>and finally an <strong>Exception</strong> with the message <em>String could not be parsed as XML</em>.</p>
  
  <p>If I remove two Unicode characters, it works (<a href="http://ideone.com/LaMvHN" rel="nofollow">http://ideone.com/LaMvHN</a>):</p>
  
  <pre><code>$str = "&lt;aoc&gt; САМОЛЕТОМ ТК Адамант,  г.Домодедово, мкр-н Востряково, Центральный просп. д.12&lt;/aoc&gt;";
                            ^
                             `-- two invisible characters have been removed here
  </code></pre>
  
  <p>How can I remove Unicode from string?</p>