Issue 4550: Avoid "using namespace std;" in included files (Take 2)

lily/script-engraver.cc

Index: lily/script-engraver.cc
diff --git a/lily/script-engraver.cc b/lily/script-engraver.cc
index eabb6942dacf6cd8af931d13b5d0d466f179e95f..30faba863b430d1e7930459d3d88a6613a47031f 100644
--- a/lily/script-engraver.cc
+++ b/lily/script-engraver.cc
@@ -35,6 +35,8 @@
 
 #include "translator.icc"
 
+using std::vector;
+
 struct Script_tuple
 {
   Stream_event *event_;