[barcode] Patch for barcode border

[Alessandro Rubini]

Hello Markus.

> The patch adds a "-B" command line switch which
> causes a thin (0.1pt) gray border to be printed outside the barcode and
> padding. This is useful when printing a grid of labels which you'll
> later be cutting up into individual labels.

Looks good, thanks. I'll apply this for sure but not now (see below).
 
> It's an extension of my previous patch (Improved layout control when
> printing tables).

I've seen the message, but I've a serious deadline on thursday and I'm
not able to check the details. I'm aware there were issues with table
printing, and I have always some issues in recovering my original
mindset when designing it (actually, I needed sheets of label myself,
and this is the reason why I wrote barcode in the first place).

So please ping me back on friday, as by then I'll surely have forgotten
the barcode queue.

thank you for your patches and your patience in waiting for me

/alessandro, who knows there are other patches in the queue as well