BulletSim: add clock and change logic for taint processing a little

so taints check if they are not in simulation time and execute
immediately if not.

OpenSim/Region/PhysicsModules/BulletS/BulletSimData.cs

@@ -100,6 +100,7 @@ public class BulletBody
     }
 }
 
+// Handle to btCollisionObject - a shape that can be added to a btRidgidBody
 public class BulletShape
 {
     public BulletShape()