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/DoubleSerializer.cs

@@ -0,0 +1,28 @@
+// 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.Collections.Generic;
+using System.Xml;
+
+namespace Microsoft.Xna.Framework.Content.Pipeline.Serialization.Intermediate
+{
+    [ContentTypeSerializer]
+    class DoubleSerializer : ElementSerializer<double>
+    {
+        public DoubleSerializer() :
+            base("double", 1)
+        {
+        }
+
+        protected internal override double Deserialize(string[] inputs, ref int index)
+        {
+            return XmlConvert.ToDouble(inputs[index++]);
+        }
+
+        protected internal override void Serialize(double value, List<string> results)
+        {
+            results.Add(XmlConvert.ToString(value));
+        }
+    }
+}