Import lwIP contrib rep

... from http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git/ into contrib/ subdir, STABLE-2_1_0_RELEASE tag
lwIP contrib is now officially frozen
TODO: Fix build

contrib/apps/LwipMibCompiler/SharpSnmpLib/Mib/Elements/IDeclaration.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Lextm.SharpSnmpLib.Mib.Elements
+{
+    public interface IDeclaration: IElement
+    {
+        /// <summary>
+        /// Name.
+        /// </summary>
+        string Name
+        {
+            get;
+        }
+    }
+}