New Post-processing Intervention Features

[shypike]

There are no pauses possible: the external par2 and unrar programs cannot be paused during their execution.

I think it's rather over the top to ask for so much interactive control for a program that's
essentially dedicated to batch processing.

[shypike]

There is already an option to stop downloading during post-processing.

The alternative of saving up all post-processing until downloading is ready, looks less useful to me.