Option to release inactive file descriptors automatically after some time

[Nirzak]

Hi, we know that after checking or downloading rtorrent keep open the file descriptor until we stop and restart seeding the file.
This creates a problem when we need to upload a file automatically using rclone vfs. rclone thinks the file is still being used. so it doesn't consider the file to upload. after I stop and restart seeding the file, then it starts to upload.

So an option like inactive_timeout=<time_in_seconds> will be really helpful. it will periodically check if a file is inactive for a particular time and will release the file descriptor once the inactive time surpasses the inactive_timeout option. Thanks.