Change LandDataSerializer deserialization so that in the future it won't care about extra elements or element order.

This brings it into line with other deserializations such as object and will improve future backward compatibility.

OpenSim/Framework/Serialization/External/UserInventoryItemSerializer.cs

@@ -41,8 +41,7 @@ namespace OpenSim.Framework.Serialization.External
 {        
     /// <summary>
     /// Serialize and deserialize user inventory items as an external format.
-    /// </summary> 
-    /// XXX: Please do not use yet.
+    /// </summary>
     public class UserInventoryItemSerializer
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);