Add Altas class & refactored Atlas editor

PckStudio.Core/Serializer/AtlasSerializer.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using OMI.Formats.Pck;
+using PckStudio.Core.Extensions;
+using PckStudio.Interfaces;
+
+namespace PckStudio.Core.Serializer
+{
+    internal sealed class AtlasSerializer : IPckAssetSerializer<Atlas>
+    {
+        public void Serialize(Atlas atlas, ref PckAsset asset)
+        {
+            asset.SetTexture(atlas);
+        }
+    }
+}