Release v1.8.4

• download_series raises IncompleteExportError on a plain download too, not only inside a backtest, after the ready files are on disk. The server now states the wall once on the manifest (wall: reason, markets withheld, rows needed to finish, reset time, upgrade link); the exception carries those as rows_needed, resets_at and upgrade_url, plus the partial result. dry_run never raises and its result exposes wall as the quote.
• SeriesDownloadResult.wall (SeriesWall), None when nothing was withheld or against older servers.