removed files of finished downloads get created after next fatrat startup

[dwatzke]

When a download is finished and you leave it in fatrat, quit fatrat, remove the file, start fatrat, then fatrat recreates those files empty - only containing zeroes. This is pointless. It would be better to just notify the user by changing the transfer icon to something else and explaining the situation in the message column

[dwatzke]

found out that this is actually a proper behavior of libtorrent when you add a torrent into the session and preallocation is set to "full" ... will look into making a workaround and forcing the "sparse" preallocation for finished torrent transfers - that should fix this bug

[LubosD]

Fixed.