Improve font display on NS port

Improve font display on NS port

* src/nsfns.m (Fx_create_frame): Use "fixed" for the default font on
GNUstep.

* src/nsfont.m (LCD_SMOOTHING_MARGIN, ns_escape_name)
(ns_unescape_name, ns_attribute_fvalue)
(STYLE_REF): Remove unused defines and functions.

(struct ns_glyph_layout, enum lgstring_direction).
(enum gs_font_slant, enum gs_font_weight, enum gs_font_width)
(enum gs_specified, struct gs_font_data): New enumerators and
structures.

(ns_font_descs_match_p)
(ns_done_font_data, ns_get_font_data): New functions.
(ns_glyph_metrics): Stop escaping names.

(ns_spec_to_descriptor): Fix font descriptor creation for symbolic
font spec entires.
(ns_descriptor_to_entity): Create entries with the correct symbolic
styles.

(ns_fallback_entity): Fix fallback entity selection.
(ns_findfonts): Use our own font matcher instead of the broken GNUstep
matcher.

(ns_list_family): Remove obsolete comment.
(nsfont_open): Remove obsolete code, comments, and synthItal logic
which doesn't work on GNUstep.

(nsfont_encode_char): Use a type that can fit NSGlyph
(nsfont_draw): Chose correct font, remove obsolete mouse face logic,
obsolete comments, and switch to using glyph-based drawing instead of
character-based drawing.

(ns_font_shape, nsfont_shape): New functions.

(ns_uni_to_glyphs_1): New function.
(ns_uni_to_glyphs): Return glyphs instead of unicode codepoints.

(ns_glyph_metrics): Use NSGlyphs instead of unicode codepoints and fix
left bearing, right bearing, ascent and descent computation.

(struct nsfont_driver): Add shaping capability.

* src/nsterm.h (struct nsfont_info): Use unsigned int for glyph cache.

* src/nsterm.c (ns_focus): Set DPS clipping on GNUstep.

(ns_compute_glyph_string_overhangs): Fix overhang computation by using
xterm code.
(ns_draw_window_cursor): Simplify cursor drawing.
(ns_maybe_dumpglyphs_background): Test for cursor HL and remove
obsolete mouse face logic.
(ns_dumpglyphs_image)
(ns_dumpglyphs_box_or_relief): Rectify for new cursor logic.
(ns_dumpglyphs_stretch): Rectify for new cursor logic and rely on
ns_draw_glyph_string to set focus.
(ns_draw_glyph_string_foreground): Remove mouse face logic.
(ns_draw_glyph_strings): Implement overhangs, remove obsolete
comment, and always focus before dumping glyphs.
(ns_draw_text_decoration): Add condition for DRAW_CURSOR and simplify
color selection.
(ns_define_frame_cursor): Remove nonsensical code (define_frame_cursor
has nothing to do with the text cursor, aka caret).

* src/xdisp.c (draw_glyphs): Enable code for NS port to fix mouse face
cursor display.

* src/macfont.m (get_cgcolor_from_nscolor): New function.
(macfont_draw): Remove obsolete mouse-face code and enable cursor
display.