feature request: pwg standard names

[bdantas]

I'm writing an application that needs to know the PWG media standardized name of user's preferred paper size. Would it be possible for libpaper to be extended to provide this information? Say, with a --pwg flag like this:

$ paper --pwg Letter
na_letter_8.5x11in

$ paper --pwg A4
iso_a4_210x297mm

[rrthomas]

Definitely, I would happily accept a patch for that.