Make arguments like Context.GrobName accessible as symbol lists

input/regression/bar-number.ly

 
-\version "2.17.5"
+\version "2.17.6"
 
 \header {
 
 texidoc="Bar numbers may be set and their padding adjusted individually.··
 The counting of bar numbers is started after the anacrusis.
 
 To prevent clashes at the beginning of a line, the padding may have to·
 be increased.
 "
 
 }
 
 \layout {
   ragged-right = ##t
 }
 
 \relative c'' {
-  \override Score.BarNumber break-visibility = #all-visible
+  \override Score.BarNumber.break-visibility = #all-visible
   \partial 4 c4·
   c1 c c
   \set Score.currentBarNumber = #99999
-  \override Score.BarNumber  padding = #3
+  \override Score.BarNumber.padding = #3
   c1 c
 }