Made AnimationEditor compatible with Dictionary SpriteMaps

Added MonoGame Pipeline's IntermediateSerializer and needed classes from the pipeline and  MonoGame.Framework.Utilities to make AnimationEditor capable of reading Dictionaries

AnimationEditor/MonoGame.Framework.Content.Pipeline/Serialization/Intermediate/EnumSerializer.cs

@@ -0,0 +1,36 @@
+// MonoGame - Copyright (C) The MonoGame Team
+// This file is subject to the terms and conditions defined in
+// file 'LICENSE.txt', which is part of this source code package.
+
+using System;
+using System.Diagnostics;
+
+namespace Microsoft.Xna.Framework.Content.Pipeline.Serialization.Intermediate
+{
+    class EnumSerializer : ContentTypeSerializer
+    {
+        public EnumSerializer(Type targetType) :
+            base(targetType, targetType.Name)
+        {
+        }
+
+        protected internal override object Deserialize(IntermediateReader input, ContentSerializerAttribute format, object existingInstance)
+        {
+            var str = input.Xml.ReadString();
+            try
+            {
+                return Enum.Parse(TargetType, str, true);
+            }
+            catch (Exception ex)
+            {
+                throw input.NewInvalidContentException(ex, "Invalid enum value '{0}' for type '{1}'", str, TargetType.Name);
+            }
+        }
+
+        protected internal override void Serialize(IntermediateWriter output, object value, ContentSerializerAttribute format)
+        {
+            Debug.Assert(value.GetType() == TargetType, "Got invalid value type!");
+            output.Xml.WriteString(value.ToString());
+        }
+    }
+}