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/Utilities/ReflectionHelpers.Default.cs

@@ -0,0 +1,36 @@
+using System;
+using System.IO;
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+namespace MonoGame.Utilities
+{
+    internal static partial class ReflectionHelpers
+    {
+        /// <summary>
+        /// Generics handler for Marshal.SizeOf
+        /// </summary>
+        internal static class SizeOf<T>
+        {
+            static int _sizeOf;
+
+            static SizeOf()
+            {
+                _sizeOf = Marshal.SizeOf<T>();
+            }
+
+            static public int Get()
+            {
+                return _sizeOf;
+            }
+        }
+
+        /// <summary>
+        /// Fallback handler for Marshal.SizeOf(type)
+        /// </summary>
+        internal static int ManagedSizeOf(Type type)
+        {
+            return Marshal.SizeOf(type);
+        }
+    }
+}