Announcing paperbackup.py to backup keys as QR codes on paper

[Gerd v. Egidy]

> I'm a little
> surprised that your code is as large as it is, too: using an alternate
> pipeline you might be able to significantly reduce code size.
> 
> (a) use Python 3's gpg module to export the secret key
> (b) paperkey --output-type raw --secret-key key.gpg --output key.raw

I want paperbackup.py to be independent and agnostic of gnupg. It should also 
be usable for e.g. ssh keys or ciphertext.

> (c) use Python 3's QR library to create a series of PNGs
> (d) use Wand or PythonMagick to convert the PNGs to PDF
> (e) save the PDF and you're done

I had some problems creating proper multipage pdfs, so I used PyX.

If you can come up with shorter sourcecode or less dependencies, I'm happy to 
take patches.

Kind regards,

Gerd