title: Rotate QGraphicsPixmapItem with mouse
body: <p>I'm writing an application in PyQt that will allow users to select
  images placed on a <code>QGraphicsScene</code> (using a custom
  <code>QGraphicsPixmapItem</code>). Upon selection I would like a rotation handle to
  appear on the image that the user can "grab" with the mouse and
  rotate, thus rotating the <code>QGraphicsPixmapItem</code>. Basically, I am looking
  for the rotation handle feature you get in PowerPoint upon selecting a
  shape. This seems like a really basic feature that many people would
  have implemented, but I cannot find any good examples on the web. Can
  anyone point me in the right direction?</p>