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/ArraySerializer.cs

@@ -0,0 +1,48 @@
+// 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.Collections.Generic;
+
+namespace Microsoft.Xna.Framework.Content.Pipeline.Serialization.Intermediate
+{
+    class ArraySerializer<T> : ContentTypeSerializer<T[]>
+    {
+        private readonly ListSerializer<T> _listSerializer;
+
+        public ArraySerializer() :
+            base("array")
+        {
+            _listSerializer = new ListSerializer<T>();
+        }
+
+        protected internal override void Initialize(IntermediateSerializer serializer)
+        {
+            _listSerializer.Initialize(serializer);
+        }
+
+        public override bool ObjectIsEmpty(T[] value)
+        {
+            return value.Length == 0;
+        }
+
+        protected internal override void ScanChildren(IntermediateSerializer serializer, ChildCallback callback, T[] value)
+        {
+            _listSerializer.ScanChildren(serializer, callback, new List<T>(value));
+        }
+
+        protected internal override T[] Deserialize(IntermediateReader input, ContentSerializerAttribute format, T[] existingInstance)
+        {
+            if (existingInstance != null)
+                throw new InvalidOperationException("You cannot deserialize an array into a getter-only property.");
+            var result = _listSerializer.Deserialize(input, format, null);
+            return result.ToArray();
+        }
+
+        protected internal override void Serialize(IntermediateWriter output, T[] value, ContentSerializerAttribute format)
+        {
+            _listSerializer.Serialize(output, new List<T>(value), format);
+        }
+    }
+}