message: Core: bugfix in IO API.
  The IO_Image_Read function did not use the idx_image_inchain parameter.
diff: @@ -110,15 +110,13 @@ int IO_N_Images_In_File( State *state, const char *file, int format, int idx_cha
  void IO_Image_Read( State *state, const char *file, int format, int idx_image_infile,
  int idx_image_inchain, int idx_chain ) noexcept
  {
  - int idx_image = -1;
  -
  try
  {
  std::shared_ptr<Data::Spin_System> image;
  std::shared_ptr<Data::Spin_System_Chain> chain;
  // Fetch correct indices and pointers
  - from_indices( state, idx_image, idx_chain, image, chain );
  + from_indices( state, idx_image_inchain, idx_chain, image, chain );
  // Read the data
  image->Lock();
  @@ -127,11 +125,11 @@ void IO_Image_Read( State *state, const char *file, int format, int idx_image_in
  Log( Utility::Log_Level::Info, Utility::Log_Sender::API,
  fmt::format("Read spins from file {} with format {}", file, format),
  - idx_image, idx_chain );
  + idx_image_inchain, idx_chain );
  }
  catch( ... )
  {
  - spirit_handle_exception_api(idx_image, idx_chain);
  + spirit_handle_exception_api(idx_image_inchain, idx_chain);
  }
  }
  