title: Rotate a point around a point with OpenCV
body: <p>Does anyone know how I can rotate a point around another in OpenCV?</p>
  
  <p>I am looking for a function like this:</p>
  
  <pre><code>Point2f rotatePoint(Point2f p1, Point2f center, float angle)
  {
      /* MAGIC */
  }
  </code></pre>