[barcode] PNG output patch

[Alessandro Rubini]

>   I've prepared a patch for the PNG output backend as described here:

Thanks. 

> - add an extra argument to Barcode_Print (would break compatibility);

Yes, that's an issue.
 
> - add an extra member to struct Barcode_Item, and a new function to
>   set it (Barcode_Config, maybe?) before calling Barcode_Print.

I prefer this way.

>   This would make PNG output from Barcode_Encode_and_Print impossible
>   (unless an extra parameter is added to it - compatibility troubles
>   again) but it looks like a minor disadvantage to me.

I agree.
 
> Those who are interested can find the patch here:
> 
> http://www.santinoli.com/software/index.html

It looks pretty good at a first sight. It might finally force me to
make a new release.

I'll try to give feedback in a while (say one week: I'm going to be
out of office for some days). Please ping me again offlist if I delay
too much.

thank you very much
/alessandro