#26 Seeding does not stop after completion of partial download

[Henry James]

When only some files of a multi-file torrent is chosen
to be downloaded, seeding does not stop after the
requested files are completed and seeding termination
criteria are met.

Reproducability: Always.

Steps to reproduce:

1. Set seeding rules to "stop when ratio reaches 1.0".
2. Start a multi-file torrent and choose to only
download one file from it.
3. Observe how seeding continues after the one file is
complete and the ratio is way beyond 1.0.

Suggestion for fix: It's possible when calculating
UL/DL ratio, Rufus wrongfully takes the size of all
files in the torrent instead of only those selected for
download. It's also possible Rufus generally consider a
download to be "not finished yet" as long as only some
files are selected for download. It's even possible
both mistakes are made.