Refactor get/set_property to take the item as first argument

lily/episema-engraver.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2010--2020 Neil Puttock <n.puttock@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
@@ skipping 44 matching lines @@
 {
   finished_ = 0;
   current_event_ = 0;
   span_ = 0;
   event_drul_.set (0, 0);
 }
 
 void
 Episema_engraver::listen_episema (Stream_event *ev)
 {
-  Direction d = to_dir (ev->get_property ("span-direction"));
+  Direction d = to_dir (get_property (ev, "span-direction"));
   // Must not ASSIGN_EVENT_ONCE here, since episema
   // can be typeset over a single neume
   event_drul_[d] = ev;
 }
 
 void
 Episema_engraver::process_music ()
 {
   if (event_drul_[START])
     {
@@ skipping 25 matching lines @@
 
 void
 Episema_engraver::typeset_all ()
 {
   if (finished_)
     {
       if (!finished_->get_bound (RIGHT))
         {
           Grob *col = (note_columns_.size ()
                        ? note_columns_.back ()
-                       : unsmob<Grob> (get_property ("currentMusicalColumn")));
+                       : unsmob<Grob> (get_property (this, "currentMusicalColumn")));
           finished_->set_bound (RIGHT, col);
         }
       finished_ = 0;
     }
 }
 
 void
 Episema_engraver::stop_translation_timestep ()
 {
   if (span_ && !span_->get_bound (LEFT))
     {
       Grob *col = (note_columns_.size ()
                    ? note_columns_.front ()
-                   : unsmob<Grob> (get_property ("currentMusicalColumn")));
+                   : unsmob<Grob> (get_property (this, "currentMusicalColumn")));
       span_->set_bound (LEFT, col);
     }
 
   typeset_all ();
   event_drul_.set (0, 0);
 }
 
 void
 Episema_engraver::finalize ()
 {
@@ skipping 41 matching lines @@
 
                 /* create */
                 "Episema ",
 
                 /* read */
                 "",
 
                 /* write */
                 ""
                );