PR #17814.
Closes#17792.
Closes#929.
(Actually it should close all issues about lack of ability to stop torrent after metadata downloaded or after files are initially checked.)
Also makes explicit the temporary start of the torrent in the case when recheck of the stopped torrent is performed.
"private" subfolders violate the structure of the project,
since the existence of all other subfolders is based on a
different principle.
In addition, there is no clear line between "private" and
"non private".
