title: PHP regex not matching right parenthisis
body: <p>im using this regex to extract salaries from a file containing many different lines of text:</p>
  
  <pre><code>/(£|\€|GBP)\s*?(.)*?(pro-rata|\x28pro-rata\x29)/i
  </code></pre>
  
  <p>The test cases are like this:</p>
  
  <blockquote>
    <p>"Relevant Quantity Surveying construction drawings Salary: £36,999 (pro-rata) in accordance with standard construction terms ..." </p>
  </blockquote>
  
  <p>It matches:</p>
  
  <ul>
  <li>£36,999 pro-rata </li>
  <li>€36,999 pro-rata </li>
  <li>GBP 36,999 pro-rata</li>
  </ul>
  
  <p>But all matches of parenthesized 'pro-rata' are missing the right parenthtisis - i.e :</p>
  
  <blockquote>
    <p>£36,999 (pro-rata</p>
  </blockquote>
  
  <p>any ideas what wrong with this???</p>