title: Username regex with special allowances
body: <p>I really need a JavaScript username regex as:</p>
  <ul>
  <li>must start with a letter</li>
  <li>from 5-20 characters.</li>
  <li>allows the following special characters after the first letter: <code>_-.@</code></li>
  <li>allows for all letters and numbers after the first character (including accented characters).</li>
  </ul>
  <p>I am pretty new to regex, and I read this which seems sort of close:</p>
  <pre><code>/^[a-zA-Z][a-zA-Z\d-_\.@]+$/ 
  </code></pre>
  <p>but it does not allow for accented characters (i.e. <strong>é</strong>) after the first character.</p>