Revert "Revert "Add experimental stubs for an extension function interface on both""

Found that the vehicle movement problem was not caused by these physics changes.

This reverts commit 89857378ce.

OpenSim/Region/Physics/Manager/PhysicsActor.cs

@@ -313,6 +313,12 @@ namespace OpenSim.Region.Physics.Manager
         public abstract void SubscribeEvents(int ms);
         public abstract void UnSubscribeEvents();
         public abstract bool SubscribedEvents();
+
+        // Extendable interface for new, physics engine specific operations
+        public virtual object Extension(string pFunct, params object[] pParams)
+        {
+            throw new NotImplementedException();
+        }
     }
 
     public class NullPhysicsActor : PhysicsActor

OpenSim/Region/Physics/Manager/PhysicsScene.cs

@@ -25,10 +25,13 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+using System;
 using System.Collections.Generic;
 using System.Reflection;
+
 using log4net;
 using Nini.Config;
+
 using OpenSim.Framework;
 using OpenMetaverse;
 
@@ -331,5 +334,11 @@ namespace OpenSim.Region.Physics.Manager
         {
             return false;
         }
+
+        // Extendable interface for new, physics engine specific operations
+        public virtual object Extension(string pFunct, params object[] pParams)
+        {
+            throw new NotImplementedException();
+        }
     }
 }