Make various tweaks to undo code in an effort to get things working better.

Undo rotation and position appear to be working.
Resizing a single prim appears to be working, though the undo has to be done twice.
Resizing a group of prims still does not work properly - possibly because in the UndoState we don't store a knowledge of when we're resizing a whole group rather than individual prims.
This needs to be addressed.

OpenSim/Region/Framework/Scenes/SceneGraph.cs

@@ -564,6 +564,7 @@ namespace OpenSim.Region.Framework.Scenes
                     part.Undo();
             }
         }
+
         protected internal void HandleRedo(IClientAPI remoteClient, UUID primId)
         {
             if (primId != UUID.Zero)