Committing the Avination Scene Presence and related texture code

- Parts of region crossing code
- New bakes handling code
- Bakes now sent from sim to sim without central storage
- Appearance handling changes
- Some changes to sitting
- A number of unrelated fixes and improvements

OpenSim/Region/CoreModules/Asset/CoreAssetCache.cs

@@ -112,6 +112,10 @@ namespace OpenSim.Region.CoreModules.Asset
         ////////////////////////////////////////////////////////////
         // IImprovedAssetCache
         //
+        public bool Check(string id)
+        {
+            return false;
+        }
 
         public void Cache(AssetBase asset)
         {