Make arguments like Context.GrobName accessible as symbol lists

input/regression/grid-lines.ly

 \header
 {
 
   texidoc = "With grid lines, vertical lines can be drawn between
 staves synchronized with the notes."
 
 }
-\version "2.17.5"
+\version "2.17.6"
 
 skips =
 {
   \time 12/8
-  \once  \override Score.GridLine thickness = #4.0
+  \once  \override Score.GridLine.thickness = #4.0
   s8·
   s8·
   s8·
-  \once  \override Score.GridLine thickness = #3.0
+  \once  \override Score.GridLine.thickness = #3.0
   s8·
   s8·
   s8·
-  \once  \override Score.GridLine thickness = #4.0
+  \once  \override Score.GridLine.thickness = #4.0
   s8·
   s8·
   s8·
-  \once  \override Score.GridLine thickness = #3.0
+  \once  \override Score.GridLine.thickness = #3.0
   s8·
   s8·
   s8·
 }
 
 
 \layout {
   \context {
     \Staff
     \consists "Grid_point_engraver"
 ····
   }
 
   \context {
     \RhythmicStaff
     \consists "Grid_point_engraver"
     gridInterval = #(ly:make-moment 1 8)
-    \override BarLine bar-extent = #'(-0.025 . 0.025)
+    \override BarLine.bar-extent = #'(-0.025 . 0.025)
   }
   \context {
     \StaffGroup
     \remove "System_start_delimiter_engraver"·
   }
   \context {
     \Score
       \consists "Grid_line_span_engraver"
-      \override SystemStartBrace transparent = ##t
+      \override SystemStartBrace.transparent = ##t
 
-      \override NoteColumn X-offset = #-0.5
-      \override NoteHead Y-offset = #0.75
+      \override NoteColumn.X-offset = #-0.5
+      \override NoteHead.Y-offset = #0.75
   }
 }
 
 \layout {
   ragged-right = ##t
 }
 \score {
 \new StaffGroup <<
   \new RhythmicStaff \with
   {
-    \override NoteHead  no-ledgers = ##t
+    \override NoteHead.no-ledgers = ##t
   }
   {
     \stemUp
     c4. c8 c8 c c4 c8 c8.[ c16 c8]
   }
   \new RhythmicStaff
   {
-    \override NoteHead transparent = ##t
-    \override NoteHead no-ledgers = ##t
-    \override Stem transparent = ##t
-    \override Flag transparent = ##t
-    \override Beam transparent = ##t
+    \override NoteHead.transparent = ##t
+    \override NoteHead.no-ledgers = ##t
+    \override Stem.transparent = ##t
+    \override Flag.transparent = ##t
+    \override Beam.transparent = ##t
     << \skips
 
                                 % force regular spacing by introducing notes.
        \repeat unfold 12 c8
      >>
   }
 ··
 >>
 }