Bunch of independent changes (ouch)

API additions:

	hb_segment_properties_t
	HB_SEGMENT_PROPERTIES_DEFAULT
	hb_segment_properties_equal()
	hb_segment_properties_hash()

	hb_buffer_set_segment_properties()
	hb_buffer_get_segment_properties()

	hb_ot_layout_glyph_class_t

	hb_shape_plan_t
	hb_shape_plan_create()
	hb_shape_plan_create_cached()
	hb_shape_plan_get_empty()
	hb_shape_plan_reference()
	hb_shape_plan_destroy()
	hb_shape_plan_set_user_data()
	hb_shape_plan_get_user_data()
	hb_shape_plan_execute()

	hb_ot_shape_plan_collect_lookups()

API changes:

	Rename hb_ot_layout_feature_get_lookup_indexes() to
	hb_ot_layout_feature_get_lookups().

New header file:

	hb-shape-plan.h

And a bunch of prototyped but not implemented stuff.  Coming soon.
(Tests fail because of the prototypes right now.)
diff --git a/src/Makefile.am b/src/Makefile.am
index aca8abf..bb7601e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -43,7 +43,6 @@
 	hb-shape.cc \
 	hb-shape-plan-private.hh \
 	hb-shape-plan.cc \
-	hb-shape-plan.h \
 	hb-shaper-list.hh \
 	hb-shaper-impl-private.hh \
 	hb-shaper-private.hh \
@@ -62,6 +61,7 @@
 	hb-font.h \
 	hb-set.h \
 	hb-shape.h \
+	hb-shape-plan.h \
 	hb-unicode.h \
 	hb-version.h \
 	$(NULL)