Separate parameter faces (those created and modified by the user)

Separate parameter faces (those created and modified by the user)
	from the computed faces (the combinations created by
	compute_char_face), so that we don't waste global face id's.
	* xterm.h (struct x_display): Replace the fields faces and n_faces
	with fields param_faces, n_param_faces, computed_faces,
	n_computed_faces, and size_computed_faces.
	(FRAME_FACES, FRAME_N_FACES): Replaced by...
	(FRAME_COMPUTED_FACES, FRAME_N_COMPUTED_FACES, FRAME_PARAM_FACES,
	FRAME_N_PARAM_FACES): New macros.
	* xfaces.c: Doc fixes.
	(init_frame_faces): Call new_computed_face to create entries for
	the default and mode line faces.  Use the FRAME...PARAM_FACES
	macros.
	(free_frame_faces): Use the FRAME...PARAM_FACES and
	FRAME...COMPUTED_FACES macros.  Don't use the copy flag; all
	parameter faces have real X resources, and all computed faces just
	have copies.  Free both the parameter and computed face arrays.
	(new_computed_face): New function.
	(intern_computed_face): Renamed from intern_frame_face; callers
	changed.  Call new_computed_face.
	(ensure_face_ready, compute_char_face, compute_glyph_face): Use the
	FRAME...PARAM_FACES macros.
	(recompute_basic_faces): Use the FRAME...PARAM_FACES and
	FRAME...COMPUTED_FACES macros.  Produce the computed faces by
	starting with the base faces and merging in the parameter faces.
	(Fset_face_attribute_internal): Use the FRAME...PARAM_FACES
	macros.  Just call recompute_basic_faces if the default or mode
	line faces have changed.
	* xfns.c (Fx_list_fonts): Use the FRAME...PARAM_FACES macros.
	* xterm.c (dumpglyphs): Use the FRAME...COMPUTED_FACES macros.
	* dispextern.h (struct face): Remove the copy member.  This is no
	longer necessary; all computed faces are copies, and no parameter
	faces are.