Improve support for WGL4 encoded fonts.
* src/psnames/psmodule.c (WGL_EXTRA_LIST_SIZE): New macro.
(ft_wgl_extra_unicodes, ft_wgl_extra_glyph_names,
ft_wgl_extra_glyph_name_offsets): New arrays.
(ps_check_wgl_name, ps_check_wgl_unicode): New functions.
(ps_unicodes_init): Use them to add additional Unicode mappings.