title: Draw rectangle with connection point using Raphael
body: <p>i'm trying to draw a rectangle with 4 connection points in each edges ( not in the corners). Like this :</p>
  
  <p><img src="https://i.stack.imgur.com/9KtCg.png" alt="enter image description here"></p>
  
  <p>Because laterly I need to use mouse event on them.</p>