* adding XmppPresenceStanza and deserialization/reification support

having reached the intermediate level of .NET's XmlSudoku, i've
  now figured out how to do deserialization using different 
  XmlSerializers (this stuff begins to grow on me, sigh).

  [still not used code, work-in-progress]

* adding convenience property on OSHttpRequest.cs (from awebb)

OpenSim/Framework/Servers/OSHttpRequest.cs

@@ -67,6 +67,11 @@ namespace OpenSim.Framework.Servers
             get { return _contentLength64; }
         }
 
+        public long ContentLength64
+        {
+            get { return _contentLength64; }
+        }
+
         public string ContentType
         {
             get { return _contentType; }