...if Pango 1.44.0+ and HarfBuzz 2.2.0+ are available, otherwise we
stick on to the current code path.
This way, we can have people build and run the demo even without
PangoFT2 if Pango 1.44.0 or later and HarfBuzz 2.2.0 or later is
installed.
Add more features to the list, allow selecting script/language
from the set that is supported by the font, indicate which
features are present in the font for the selected script/language,
and expand the default specimen to cover latin, cyrillic and
greek.
