Is your feature request related to a problem? Please describe.
When starting the download of many files (clicking multiple Magnet links on a page for e.g.) the confirmation dialog showing where the download will be saved always pops up. In Transmission for e.g. there's an option to not prompt each time.

Describe the solution you'd like
Add a checkbox in the preferences that prevents t

Instead of always allocating a fixed size buffer (1,000,000 bytes currently), it should leverage the upfront knowledge of total size of the metadata and allocate Math.min(DEFAULT_BUFFER_LEN, metadata.length()).

Now I use a SQL to cleanup torrents belongs to nobody.

DELETE
FROM torrents
WHERE id NOT IN (
  SELECT torrent_id
  FROM user_torrents
)

This should be done automatically.