Adds stem acknowledgement to beam collision engraver to fix issue 795. (issue4337045)

[mtsolo]

Reviewers: ,

Message:
Cheers,
Mike

Description:
Adds stem acknowledgement to beam collision engraver to fix issue 795.

Please review this at http://codereview.appspot.com/4337045/

Affected files:
  M lily/beam-collision-engraver.cc


Index: lily/beam-collision-engraver.cc
diff --git a/lily/beam-collision-engraver.cc  
b/lily/beam-collision-engraver.cc
index  
a12311602cc5ff1c5ffc579f9823dbe6b5b9888a..ceec9c5af9cc8f290801166fea1b6cc724cbeb1c  
100644
--- a/lily/beam-collision-engraver.cc
+++ b/lily/beam-collision-engraver.cc
@@ -30,6 +30,7 @@ protected:
   vector<Grob *> covered_grobs_;

   DECLARE_ACKNOWLEDGER (note_head);
+  DECLARE_ACKNOWLEDGER (stem);
   DECLARE_ACKNOWLEDGER (accidental);
   DECLARE_ACKNOWLEDGER (clef);
   DECLARE_ACKNOWLEDGER (key_signature);
@@ -96,6 +97,12 @@ Beam_collision_engraver::acknowledge_note_head  
(Grob_info i)
 }

 void
+Beam_collision_engraver::acknowledge_stem (Grob_info i)
+{
+  covered_grobs_.push_back (i.grob ());
+}
+
+void
 Beam_collision_engraver::acknowledge_accidental (Grob_info i)
 {
   if (i.grob ()->internal_has_interface (ly_symbol2scm  
("inline-accidental-interface")))
@@ -130,6 +137,7 @@ Beam_collision_engraver::acknowledge_beam (Grob_info i)
 #include "translator.icc"

 ADD_ACKNOWLEDGER (Beam_collision_engraver, note_head);
+ADD_ACKNOWLEDGER (Beam_collision_engraver, stem);
 ADD_ACKNOWLEDGER (Beam_collision_engraver, accidental);
 ADD_ACKNOWLEDGER (Beam_collision_engraver, clef);
 ADD_ACKNOWLEDGER (Beam_collision_engraver, key_signature);