Skip if converted file has larger size than the original

[ikun]

As title. Sometimes I have to convert thousands of image files to save space. Those files normally spreads in many sub-folders, and so I prefer to ask xnconvert to delete the original files after conversion. However, it cannot be ensured that the converted image always has smaller size than the original, while it is just too annoying to check the output log to find out and remove those unexpected converted files and recover the original files.

Seems the compression ratios are calculated in the output log, so I wonder if there could be a new option that can "remove the converted file instead if it has larger size than the original" (maybe by checking if the compression ratio is larger than -1%) when "delete original" is ticked.