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/ListSerializer.cs

@@ -0,0 +1,82 @@
+// 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
+{
+    [ContentTypeSerializer]
+    class ListSerializer<T> : ContentTypeSerializer<List<T>>
+    {
+        private ContentTypeSerializer _itemSerializer;
+
+        public ListSerializer() :
+            base("list")
+        {
+        }
+
+        public override bool CanDeserializeIntoExistingObject
+        {
+            get { return true; }
+        }
+
+        protected internal override void Initialize(IntermediateSerializer serializer)
+        {
+            _itemSerializer = serializer.GetTypeSerializer(typeof(T));
+        }
+
+        public override bool ObjectIsEmpty(List<T> value)
+        {
+            return value.Count == 0;
+        }
+
+        protected internal override void ScanChildren(IntermediateSerializer serializer, ChildCallback callback, List<T> value)
+        {
+            foreach (var item in value)
+                callback(_itemSerializer, item);
+        }
+
+        protected internal override List<T> Deserialize(IntermediateReader input, ContentSerializerAttribute format, List<T> existingInstance)
+        {
+            var result = existingInstance ?? new List<T>();
+
+            var elementSerializer = _itemSerializer as ElementSerializer<T>;
+            if (elementSerializer != null)
+                elementSerializer.Deserialize(input, result);
+            else
+            {
+                // Create the item serializer attribute.
+                var itemFormat = new ContentSerializerAttribute();
+                itemFormat.ElementName = format.CollectionItemName;
+
+                // Read all the items.
+                while (input.MoveToElement(itemFormat.ElementName))
+                {
+                    var value = input.ReadObject<T>(itemFormat, _itemSerializer);
+                    result.Add(value);
+                }
+            }
+
+            return result;
+        }
+
+        protected internal override void Serialize(IntermediateWriter output, List<T> value, ContentSerializerAttribute format)
+        {
+            var elementSerializer = _itemSerializer as ElementSerializer<T>;
+            if (elementSerializer != null)
+                elementSerializer.Serialize(output, value);
+            else
+            {
+                // Create the item serializer attribute.
+                var itemFormat = new ContentSerializerAttribute();
+                itemFormat.ElementName = format.CollectionItemName;
+
+                // Read all the items.
+                foreach (var item in value)
+                    output.WriteObject(item, itemFormat, _itemSerializer);
+            }
+        }
+    }
+}