Handle system default font and changing font parameters.

Handle system default font and changing font parameters.

* xterm.h (struct x_display_info): Add atoms and Window for xsettings.

* xterm.c (handle_one_xevent): Call xft_settings_event for
ClientMessage, PropertyNotify and DestroyNotify.
(x_term_init): If we have XFT, get DPI from Xft.dpi.
Call xsettings_initialize.

* xftfont.c (xftfont_fix_match): New function.
(xftfont_open): Call XftDefaultSubstitute before XftFontMatch.
Call xftfont_fix_match after XftFontMatch.

* xfont.c (xfont_driver): Initialize all members.

* xfns.c (x_default_font_parameter): Try font from Ffont_get_system_font.
Do not get font from x_default_parameter if we got one from
Ffont_get_system_font.
(Fx_select_font): Get the defaut font name from :name of FRAME_FONT (f).

* w32font.c (w32font_driver): Initialize all members.

* termhooks.h (enum event_kind): CONFIG_CHANGED_EVENT is new.

* lisp.h: Declare syms_of_xsettings.

* keyboard.c (kbd_buffer_get_event, make_lispy_event): Handle
CONFIG_CHANGED_EVENT.

* ftfont.c (ftfont_filter_properties): New function.

* frame.c (x_set_font): Remove unused variable lval.

* font.h (struct font_driver): filter_properties is new.

* font.c (font_put_extra): Don't return if val is nil, it means
boolean option is off.
(font_parse_fcname): Collect all extra properties in extra_props
and call filter_properties for all drivers with extra_props and
font as parameter.
(font_open_entity): Do not use cache, it does not pick up new fontconfig
settings like hinting.
(font_load_for_lface): If spec had a name in it, store it in entity.

* emacs.c (main): Call syms_of_xsettings

* config.in: HAVE_GCONF is new.

* Makefile.in (GCONF_CFLAGS, GCONF_LIBS): New variables for HAVE_GCONF.
xsettings.o is new.

* menu-bar.el: Put "Use system font" in Option-menu.

* loadup.el: If feature system-font-setting or font-render-setting is
there, load font-setting.

* Makefile.in (ELCFILES): font-settings.el is new.
* font-setting.el: New file.

* NEWS: Mention dynamic font changes (font-use-system-font).

* configure.in: New option: --with(out)-gconf.
Set HAVE_GCONF if we find gconf.