title: preg_split() problem with strings containing '&'
body: <p>I am using <code>preg_split()</code> to get array of sentence from a string. </p>
  
  <pre><code>$sentences = preg_split("/([.?!\r\n]+)/", $text, 0, PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE);
  </code></pre>
  
  <p>But when <code>$text</code> contains '&amp;', for example:</p>
  
  <pre><code>$text = 'this is test. we are testing this &amp; we are over.';
  </code></pre>
  
  <p>then it stops matching after the '&amp;'.</p>