Change hb_shape() API back to what it was, add hb_shape_full()

I disliked changing hb_shape() API, and disliked the fact that it was
returning a bool now.  So, reverted.  Added new API for the extra
functionality.
diff --git a/src/hb-shape.h b/src/hb-shape.h
index b2193f7..75818dc 100644
--- a/src/hb-shape.h
+++ b/src/hb-shape.h
@@ -42,13 +42,19 @@
 } hb_feature_t;
 
 
-hb_bool_t
+void
 hb_shape (hb_font_t           *font,
 	  hb_buffer_t         *buffer,
 	  const hb_feature_t  *features,
-	  unsigned int         num_features,
-	  const char          *shaper_options,
-	  const char         **shaper_list);
+	  unsigned int         num_features);
+
+hb_bool_t
+hb_shape_full (hb_font_t           *font,
+	       hb_buffer_t         *buffer,
+	       const hb_feature_t  *features,
+	       unsigned int         num_features,
+	       const char          *shaper_options,
+	       const char         **shaper_list);
 
 
 HB_END_DECLS