Add persistence of active gestures. This needs an UGAIM update to work.

Active gestures are sent as part of the login-response. Added
fetchActiveGestures to SQLite and MySQL; added an empty one for MSSQL and
NHibernate. Using the empty ones won't cause errors, but doesn't provide
persistence either, of course.

OpenSim/Framework/Communications/InventoryServiceBase.cs

@@ -148,6 +148,15 @@ namespace OpenSim.Framework.Communications
         // See IInventoryServices
         public abstract void RequestInventoryForUser(UUID userID, InventoryReceiptCallback callback);
 
+        public List<InventoryItemBase> GetActiveGestures(UUID userId)
+        {
+            foreach (IInventoryDataPlugin plugin in m_plugins)
+            {
+                return plugin.fetchActiveGestures(userId);
+            }
+            return new List<InventoryItemBase>();
+        }
+
         #endregion
 
         #region Methods used by GridInventoryService