use fonts which will work for many languages

The command line shows this error:
./olpcgames/pangofont.py:127: PangoWarning: pango_context_load_font: assertion `pango_font_description_get_family (desc) != NULL' failed
  (logical, ink) = layout.get_pixel_extents()
This warning appears even on the OLPC. The Pangofont may be optimized for internationalization on the OLPC, which is quite important to the project.
This warning does not appear to impede the software, although the text labels show up smaller on Ubuntu than on the OLPC. It would be nice to have zero warnings for developers who may watch the command line output.