THRIFT-4609 keep InnerException wherever appropriate
Client: C#
Patch: Jens Geyer

This closes #1576
diff --git a/lib/csharp/src/TApplicationException.cs b/lib/csharp/src/TApplicationException.cs
index 0c5b08b..8dd7ae5 100644
--- a/lib/csharp/src/TApplicationException.cs
+++ b/lib/csharp/src/TApplicationException.cs
@@ -40,7 +40,7 @@
         }
 
         public TApplicationException(ExceptionType type, string message)
-            : base(message)
+            : base(message, null) // TApplicationException is serializable, but we never serialize InnerException
         {
             this.type = type;
         }