Uses Stem::beam_end_corrective to get tremolo heights right (issue 5133042)

[mtsolo]

Reviewers: ,

Message:
Hey all,

This fixes issue 1929 and gets StemTremolo placement correct for beams.
I still need to run regtests on it.

Cheers,
MS

Description:
Uses Stem::beam_end_corrective to get tremolo heights right

Please review this at http://codereview.appspot.com/5133042/

Affected files:
  M lily/stem-tremolo.cc


Index: lily/stem-tremolo.cc
diff --git a/lily/stem-tremolo.cc b/lily/stem-tremolo.cc
index  
a45ae1182abee4b71c609842cc2c362a1e3f35ee..9f21c466c3e5932764fc2bc29b67988fa5e9694b  
100644
--- a/lily/stem-tremolo.cc
+++ b/lily/stem-tremolo.cc
@@ -265,7 +265,8 @@ Stem_tremolo::y_offset (Grob *me, bool pure)

   Real end_y
     = stem->extent (stem, Y_AXIS)[stemdir]
-      - stemdir * max (beam_count, 1) * beam_translation;
+      - stemdir * max (beam_count, 1) * beam_translation
+      - Stem::beam_end_corrective (stem);

   if (!beam && Stem::duration_log (stem) >= 3)
     {