applyResumeData

Apply fast-resume atp without hashing: whole pieces in AddTorrentParams.havePieces are flushed into the picker as had (piece_flushed, which is documented safe to call straight from open for exactly this), and each block recorded in AddTorrentParams.unfinishedPieces is marked finished so the picker won't re-request the partial-piece progress already on disk. Saved stats, the sequential flag and piece/file priorities are restored too. The port of torrent adopting resume data.