Moved prim crossing out of OGS1 and into RESTComms and LocalInterregionComms. This breaks interregion comms with older versions in what concerns prim crossing. In the process of moving the comms, a few things seem to be working better, namely this may address mantis #3011, mantis #1698. Hopefully, this doesn't break anything else. But I'm still seeing weirdnesses with attchments jumping out of place after a cross/TP.

The two most notable changes in the crossing process were:
* Object gets passed in only one message, not two as done before.
* Local object crossings do not get serialized, as done before.

OpenSim/Region/Framework/Interfaces/ISceneObject.cs

@@ -0,0 +1,16 @@
+using System;
+using OpenMetaverse;
+
+namespace OpenSim.Region.Framework.Interfaces
+{
+    public interface ISceneObject
+    {
+        UUID UUID { get; }
+        ISceneObject CloneForNewScene();
+        string ToXmlString2();
+        string ExtraToXmlString();
+        void ExtraFromXmlString(string xmlstr);
+        string GetStateSnapshot();
+        void SetState(string xmlstr, UUID regionID);
+    }
+}