Ctrl c - sig hup finishes current transfers then exits

this is similar to ffmpeg - where it will receive the first ctrl-c -- and then continue to the next b frame and write out the end file metadata which makes a valid video file. on two CTRL-C's it is a sigkill and it exits immediatley.

If I have 12 transfers going and I want to cancel would be neat to hit CTRL-C or send a sighup to the PID and have it finish what its doing without having to loose out on 20GB transfers.

Ya?

There is an issue about this already I'm sure....

We could also make an rc call to do this.