[barcode] PNG output patch

[David Santinoli]

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

http://lists.linux.it/pipermail/barcode/2005-April/000242.html

The added code, however, requires one more small step to be completely
usable.  Namely, the libgd backend is passed a font path (for the ASCII
caption) which is currently hardcoded but ought to be configurable.

I am looking for advice on the best way to integrate this new parameter
into the library API.  These are the alternatives I see:

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

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

Those who are interested can find the patch here:

http://www.santinoli.com/software/index.html

Thanks,
 David