fix damping in RotationalSpring

Author: stefanstarstable

src/objects/RotationalSpring.js

@@ -52,7 +52,7 @@ RotationalSpring.prototype.applyForce = function(){
         x = bodyB.angle - bodyA.angle,
         u = bodyB.angularVelocity - bodyA.angularVelocity;
 
-    var torque = - k * (x - l) - d * u * 0;
+    var torque = - k * (x - l) - d * u;
 
     bodyA.angularForce -= torque;
     bodyB.angularForce += torque;