title: Convert rotation angle in world space to local space cocos2d
body: <p>Is there a simple way (ie an api) that converts an angle of rotation in world space to local space of a CCNode?  I know the angle of rotation a node needs to have on the screen, but the node is nested deeply in node hierarchy and I would like to set its angle so that it matches what I want.  If there's no api, what CC api calls should I make?  Something like this:</p>
  
  <pre><code>CCNode * myLocalNode;
  float myLocalAngle = CCAngleConvertFromWorldToNode(myLocalNode,myWorldAngle);
  myLocalNode -&gt; setRotation(myLocalAngle);
  </code></pre>