- added function to mark a channel for swapping + swap with current channel

- replaced misuse of "FileLoadException" with a custom LoaderException to handle file loading issues with better continue/fail logic
- removed "Save As" and replaced it with "Convert list" menu item that shows information on how to use a reference list instead of direct conversion

source/ChanSort.Loader.Android/AldenSerializer.cs

@@ -97,7 +97,7 @@ namespace ChanSort.Loader.Android
       {
         cmd.CommandText = $"select count(1) from sqlite_master where type='table' and name='{table}'";
         if ((long)cmd.ExecuteScalar() == 0)
-          throw new FileLoadException(ERR_UnknownFormat);
+          throw LoaderException.TryNext(ERR_UnknownFormat);
       }
 
       var columns = "_id, type, service_type, original_network_id, transport_stream_id, service_id, display_number, display_name, browsable, searchable, locked, "

source/ChanSort.Loader.Android/AndroidPlugin.cs

@@ -17,7 +17,7 @@ namespace ChanSort.Loader.Android
       if (file.StartsWith("dvr_rtk_tv") && file.EndsWith(".db"))
         return new AldenSerializer(inputFile);
 
-      throw new FileLoadException(SerializerBase.ERR_UnknownFormat);
+      throw LoaderException.TryNext(SerializerBase.ERR_UnknownFormat);
     }
   }
 }