Make GetSupersededType work with any message version hierarchy (#902)

MessageVersionStack.GetSupersededType uses Type.GetInterfaces which does not
offer any order guarantees. When selecting the superseded type for a message, we could sort
by class name, but that would just introduce a limitation on message naming.

Instead of that, let's call GetInterfaces for type and type.BaseType, and grab the ISupersede
entries from those. The one that does not exist in base type's list is the correct superseded type.

Author: sandst1

Source/EasyNetQ.Tests/MessageVersioningTests/MessageVersionStackTests.cs

@@ -35,6 +35,24 @@ public void Versioned_message_stack_works_for_more_than_two_versions_and_types_a
             Assert.Equal(typeof(MyMessageV3), stack.ElementAt( 2 ));
         }
 
+        [Fact]
+        public void Versioned_message_stack_works_with_arbitrary_type_names()
+        {
+            var stack = new MessageVersionStack( typeof( ComplexMessage ));
+
+            Assert.Equal(typeof(SimpleMessage), stack.ElementAt( 0 ));
+            Assert.Equal(typeof(AdvancedMessage), stack.ElementAt( 1 ));
+            Assert.Equal(typeof(ComplexMessage), stack.ElementAt( 2 ));
+        }
+
+        [Fact]
+        public void If_given_just_an_object_the_stack_can_handle_it_without_exceptions()
+        {
+            var stack = new MessageVersionStack( typeof( object ));
+        
+            Assert.Equal(typeof(object), stack.ElementAt( 0 ));
+        }
+
         [Fact]
         public void Pop_returns_the_top_of_the_stack()
         {
@@ -73,4 +91,19 @@ public class MyOtherMessage : MyMessage, ISupersede<MyMessageV2>
     {
         public int AnotherNumber { get; set; }
     }
+
+    public class SimpleMessage
+    {
+        public string Message { get; set; }
+    }
+
+    public class AdvancedMessage : SimpleMessage, ISupersede<SimpleMessage>
+    {
+        public string VeryAdvanced { get; set; }
+    }
+
+    public class ComplexMessage : AdvancedMessage, ISupersede<AdvancedMessage>
+    {
+        public string SoComplex { get; set; }
+    }    
 }

Source/EasyNetQ/MessageVersioning/MessageVersionStack.cs

@@ -56,11 +56,21 @@ private static Stack<Type> ExtractMessageVersions( Type type )
 
         private static Type GetSupersededType( Type type )
         {
-             return type
+            if( type.BaseType == null )
+                return null;
+
+            var types = FindSupersedes(type);
+            var parentTypes = FindSupersedes(type.BaseType);
+
+            return types.Except(parentTypes).FirstOrDefault();
+        }
+
+        private static IEnumerable<Type> FindSupersedes( Type type )
+        {
+            return type
                 .GetInterfaces()
                 .Where( t => t.GetTypeInfo().IsGenericType && t.GetGenericTypeDefinition() == typeof( ISupersede<> ) )
-                .SelectMany( t => t.GetGenericArguments() )
-                .LastOrDefault();
+                .SelectMany( t => t.GetGenericArguments() );                
         }
 
         private static void EnsureVersioningValid( Type messageType, Type supersededType )