ChlFileSerializer converted to a SerializerBase subclass so it can use the same reference list logic as TV data files

source/ChanSort.Loader.RefList/RefSerializerPlugin.cs

@@ -0,0 +1,16 @@
+using ChanSort.Api;
+
+namespace ChanSort.Loader.RefList
+{
+  public class RefSerializerPlugin : ISerializerPlugin
+  {
+    public string PluginName => "ChanSort Reference List";
+
+    public string FileFilter => "*.txt;*.chl";
+    
+    public SerializerBase CreateSerializer(string inputFile)
+    {
+      return new RefSerializer(inputFile);
+    }
+  }
+}