Added IRegionCreator interface that all ApplicationPlugins that are creators of Scenes should implement and register with the ApplicationRegistry.StackModuleInterface<>(); So that other plugins can attach to their OnNewRegionCreated event.

Made some changes to IRegistryCore and RegistryCore so they support "Stacked" interfaces.

OpenSim/Framework/IRegionCreator.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace OpenSim.Framework
+{
+    public delegate void NewRegionCreated(IScene scene);
+    public interface IRegionCreator
+    {
+        event NewRegionCreated OnNewRegionCreated;
+    }
+}

OpenSim/Framework/IRegistryCore.cs

@@ -4,10 +4,13 @@ using System.Text;
 
 namespace OpenSim.Framework
 {
-    public interface IRegistryCore
+    public interface IRegistryCore 
     {
         T Get<T>();
         void RegisterInterface<T>(T iface);
         bool TryGet<T>(out T iface);
+
+        void StackModuleInterface<M>(M mod);
+        T[] RequestModuleInterfaces<T>();
     }
 }

OpenSim/Framework/RegistryCore.cs

@@ -40,5 +40,15 @@ namespace OpenSim.Framework
             return (T)m_moduleInterfaces[typeof(T)];
         }
 
+        public void StackModuleInterface<M>(M mod)
+        {
+
+        }
+
+        public T[] RequestModuleInterfaces<T>()
+        {
+            return new T[] { default(T) };
+        }
+
     }
 }