- added experimental support for Loewe / Hisense 2017 servicelist.db

file format
- show error message when trying to open a .zip file that doen't contain
  the expected files of a Samsung J series or Toshiba .zip channel list
- show error message when trying to open a broken .zip file, which is
  most likely caused by exporting to a USB stick formatted with NTFS
- allow changing the "crypt" flag for Samsung .scm lists
- iterating through loaders supporting a file extension till one can read the file

source/ChanSort.Api/Model/ChannelInfo.cs

@@ -50,6 +50,7 @@ namespace ChanSort.Api
     public int ProgramNrPreset { get; set; }
 
     public bool IsNameModified { get; set; }
+    public bool IsProxy => this.RecordIndex < 0;
 
     #region ctor()
     protected ChannelInfo()