#56 Feature request: Archive file

I know d-fi skips already downloaded files but I like to move the files after they are downloaded to a different location. Would it be possible to have an archive file similar to youtube-dl's --download-archive which saves all downloaded song's IDs into a text file so d-fi will not download those again? Adding the --download-archive options could save the `playlist_id-song_id` for each downloaded file allowing for repeat songs to be downloaded across multiple playlists.