Switched C# accessors from classes to structs

net/FlatBuffers/Struct.cs

@@ -19,9 +19,9 @@ namespace FlatBuffers
     /// <summary>
     /// All structs in the generated code derive from this class, and add their own accessors.
     /// </summary>
-    public abstract class Struct
+    public struct Struct
     {
-        protected int bb_pos;
-        protected ByteBuffer bb;
+        public int bb_pos;
+        public ByteBuffer bb;
     }
-}
+}