Attempt at restoring inventory access after TPs/crossings. RemoveClient in Scene was being too

aggressive at nixing the user out of the cache. We're now relying on NeedSceneCacheClear to decide
whether to nix it or not. All other mods in other files are for better debugging messages.

OpenSim/Framework/Communications/Cache/CachedUserInfo.cs

@@ -194,6 +194,7 @@ namespace OpenSim.Framework.Communications.Cache
         /// </summary>
         public void DropInventory()
         {
+            m_log.Debug("[INVENTORY CACHE]: DropInventory called");
             // Make sure there aren't pending requests around when we do this
             // FIXME: There is still a race condition where an inventory operation can be requested (since these aren't being locked).
             // Will have to extend locking to exclude this very soon.