Move NZBs when download completes.

[E71]

Hi.

I was thinking of an option that would be nice to have:

When a download is completed, the NZB is moved from the NZB backup folder to another one designated for completed downloads.

This would come in handy if you lose your queue and want to know which NZBs were still not downloaded.

Thanks,
E71

[shypike]

The next release (0.5.0) will store the history in a separate sqlite database.
That will make at least the history a lot more robust (and independent of the queue).