Program fails with empty newline at the end of input txt file

[DavidMChan]

There's an issue with the robustness of the extractor where it fails when an extra empty new-line is added at the end of the input image list. There should be a check at dataset.lua, line 63.

Something along the lines of

for line in io.lines(imagePathFile) do
      if line != nil or line !='' then
            local id_path_label = line:split("\t")
            ffi.copy(id_data, id_path_label[1])
            ffi.copy(path_data, id_path_label[2])

            id_data = id_data + idMaxLength
            path_data = path_data + pathMaxLength

            if self.verbose and count % 10000 == 0 then
               xlua.progress(count, length)
            end;
            count = count + 1
      end;
     
end

If this check isn't there then the program will crash on the copy statement.