title: Raphael element.animate(...) - Specify a callback to be executed at every step of animation
body: <p>Using Raphael I have to move some circles (nodes) with some lines (edges) connected.
  When I change the (cx,cy) properties of a circle, I have to refresh the lines connected to that circle (using a refresh function).</p>
  
  <p>Without animation, all is fine</p>
  
  <pre><code>circle.attr({
    cx : newCx,
    cy : newCy
  })
  refreshEdges()
  </code></pre>
  
  <p>Now, if I want to use animation...</p>
  
  <pre><code>circle.animate({
    cx : newCx,
    cy : newCy
  },1000)
  </code></pre>
  
  <p>...the circle starts to move and reach the final position in 1000ms.
  But during the animation, the lines (edges) connected to that circle are not moving because the refresh funcion is not called.</p>
  
  <p>So the question is: There is a way to specify to .animate() a sort of "step" callback that Raphael will call at each step of the animation?</p>
  
  <p>I know that with jQuery that step callback can be specified as a parameter of .animate()...I hope there will be a way to do it also with Raphael :)</p>
  
  <p>Thank you!!</p>