Doc: Bar_engraver is required for system-start clefs (2694) (issue 6446160)

[tdanielsmusic]

Reviewers: ,

Message:
This minor change hardly needs the full review
machinery, especially as I've checked it with
a make doc.

Should I should push directly to staging?

Trevor


Description:
Doc: Bar_engraver is required for system-start clefs (2694)

Add sentence to doc string of Bar_engraver

Please review this at http://codereview.appspot.com/6446160/

Affected files:
  M lily/bar-engraver.cc


Index: lily/bar-engraver.cc
diff --git a/lily/bar-engraver.cc b/lily/bar-engraver.cc
index  
b2594a2cb871a8f4b5cff207083e36b18245aaf3..ac43f31bb515636f298d3c48c9d2114679b64223  
100644
--- a/lily/bar-engraver.cc
+++ b/lily/bar-engraver.cc
@@ -115,7 +115,8 @@ ADD_TRANSLATOR (Bar_engraver,
                 /* doc */
                 "Create barlines.  This engraver is controlled through the"
                 " @code{whichBar} property.  If it has no bar line to  
create,"
-                " it will forbid a linebreak at this point.",
+                " it will forbid a linebreak at this point.  This engraver"
+                " is required to trigger the creation of system-start  
clefs.",

                 /* create */
                 "BarLine ",