UPnP support added: get external ip, add forwarding rule and delete forwarding rule

Lidgren.Network/NetPeerConfiguration.cs

@@ -39,6 +39,7 @@ namespace Lidgren.Network
 		internal float m_pingInterval;
 		internal bool m_useMessageRecycling;
 		internal float m_connectionTimeout;
+		internal bool m_enableUPnP;
 
 		internal NetIncomingMessageType m_disabledTypes;
 		internal int m_port;
@@ -243,6 +244,20 @@ namespace Lidgren.Network
 			}
 		}
 
+		/// <summary>
+		/// Enables UPnP support; enabling port forwarding and getting external ip
+		/// </summary>
+		public bool EnableUPnP
+		{
+			get { return m_enableUPnP; }
+			set
+			{
+				if (m_isLocked)
+					throw new NetException(c_isLockedMessage);
+				m_enableUPnP = value;
+			}
+		}
+
 		/// <summary>
 		/// Gets or sets the local ip address to bind to. Defaults to IPAddress.Any. Cannot be changed once NetPeer is initialized.
 		/// </summary>