(uvs_area, uvs_label): New variables.

(uvs_area, uvs_label): New variables.
(sub14, uvs): New variable.
(update_uvs_area): New function.
(update_seq_area): Set `glyph_id' member only when no charmap is
used.
(update_render_area): Handle a variation selector.
(UVSProc): New function.
(RenderProc): Call update_uvs_area if the font is OpenType.
(create_widgets): Create uvs_area widget if the font has variation
selector.
(main): Setup sub14. Set font in gc_set.