* configure.in: disable pangox, xft, glx drawing if run invoked with the
	--without-x flag.
* vte.pc.in: include CFLAGS found by AC_PATH_XTRA when built with X.
* src/iso2022.c(_vte_iso2022_substitute_single): clean up and ensure that
	ambiguous widths are respected.
* src/iso2022.c, src/iso2022.h: add _vte_iso2022_unichar_width().
* src/vte.c: remove old xft2/xft1/pango/pangox/core drawing code, making draw
	the only supported method.  Remove most dependencies on gdkx and Xlib,
	except for root pixmap ID watching.
* src/vtedraw.c: only use pangox, xft if X_DISPLAY_MISSING is not defined.
* src/vtedraw.c, src/vtedraw.h: add get_using_fontconfig() method.
* src/vte.c(vte_terminal_get_using_xft): use _vte_draw_get_using_fontconfig(),
	which is what apps really want to know when they call this function.
* src/vtegl.c: wrap in #ifndef X_DISPLAY_MISSING.
* src/vtepangox.c: wrap in #ifndef X_DISPLAY_MISSING.
* src/vtexft.c: wrap in #ifndef X_DISPLAY_MISSING.
* src/vteglyph.c(_vte_glyph_cache_set_description): use horizontal advance
	instead of bitmap width when calculating display widths.
	Rename to _vte_glyph_cache_set_font_description.