#144 Add ability to restart a stuck download.

[petrifiedwood]

I would like to see the ability to right click on a
stuck download and then select an option to restart the
download. I experience many files that stick. Even
torrents. Instead of clearing the download for a
second try I would like to restart it from the download
screen since everything that is needed seems to be
right there. It would be nice to even be able to
select multiple stalled files to restart at the same
time. This would save me a bunch of time.