(ftfont_pattern_entity): Argument FRAME removed. Make

(ftfont_pattern_entity): Argument FRAME removed.  Make
a font-entity by font_make_entity.  Use font_intern_prop instead
of intern_downcase.  Use FONT_SET_STYLE to set a style-related
font property.  If a font is scalable, set avgwidth property to 0.
Set font-entity property by font_put_extra.
(ftfont_list_generic_family): Argument SPEC and REGISTRY removed.
(ffont_driver): Adjusted for the change of struct font_driver.
(ftfont_spec_pattern): New function.
(ftfont_list): Return a list, not vector.
(ftfont_match): Use ftfont_spec_pattern to get a pattern.
(ftfont_list_family): Don't downcase names.
(ftfont_free_entity): Deleted.
(ftfont_open): Return a font-ojbect.  Adjusted for the change of
struct font.  Get underline_thickness and underline_position from
font property.  Don't update dpyinfo->smallest_font_height and
dpyinfo->smallest_char_width.
(ftfont_close): Don't free `struct font'.
(ftfont_has_char): Adjusted for the format change of font-entity.
(ftfont_encode_char, ftfont_text_extents): Likewise.