nzb watch folder: accept a rar of rar'ed nzb

[af22]

I would like to be able to load a rar file containing several rar'ed nzbs into sabnzbd.

Currently, it works fine with a rar file containing nzbs, but I would like it to go down another level.

This is common when I get a group of nzb's structured like:

group_of_nzb.rar
- nzb1.rar
  - nzb1.nzb
- nzb2.rar
  - nzb2.nzb
- nzb3.rar
  - nzb3.nzb

[shypike]

I'm afraid that would mean a lot of coding for a rather rare use case.
I'll put it on the wish list, but it won't have a high priority.