title: Change the Hue of a RGB Color in javascript
body: <p>Similar to <a href="https://stackoverflow.com/questions/6443990/javascript-calculate-brighter-colour">this</a> (how to increase brightness) I want to change the Hue of a RGB (Hex) Color.</p>
  
  <p>Say <code>changeHue("#FF0000", 40)</code> returns <code>"#FFAA00"</code>  </p>