Make arguments like Context.GrobName accessible as symbol lists

Documentation/ly-examples/tab-example.ly

-\version "2.17.5"
+\version "2.17.6"
 
 #(set-global-staff-size 22.45)
 
 #(define (glissando::calc-extra-dy grob)
    (let* ((original (ly:grob-original grob))
           (left-bound (ly:spanner-bound original LEFT))
           (right-bound (ly:spanner-bound original RIGHT))
           (left-pitch (ly:event-property (event-cause left-bound) 'pitch))
           (right-pitch (ly:event-property (event-cause right-bound) 'pitch)))
 
@@ skipping 28 matching lines @@
   s2 s8 < e'-3 >4. ~
   e4 \hideNotes \grace { b8 \glissando s4 } \unHideNotes < e-2 >4\5 e,2 ~
   e2 < e'\6\harmonic >
 }
 
 \score {
   \new StaffGroup <<
     \new Staff = "guitar" <<
       \context Voice = "upper guitar" {
         \clef "G_8" \voiceOne
-        \override Glissando gap = #0.5
-        \override Glissando extra-offset = #'(-0.5 . 0)
-        \override Glissando springs-and-rods = #ly:spanner::set-spacing-rods
-        \override Glissando minimum-length = #4
-        \override Glissando extra-dy = #glissando::calc-extra-dy
+        \override Glissando.gap = #0.5
+        \override Glissando.extra-offset = #'(-0.5 . 0)
+        \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
+        \override Glissando.minimum-length = #4
+        \override Glissando.extra-dy = #glissando::calc-extra-dy
         \upper
       }
       \context Voice = "lower guitar" {
         \clef "G_8" \voiceTwo
-        \override Glissando bound-details.right.padding = #1
-        \override Glissando bound-details.left.padding = #0.2
+        \override Glissando.bound-details.right.padding = #1
+        \override Glissando.bound-details.left.padding = #0.2
         \lower
       }
     >>
     \new TabStaff = "tab" <<
       \context TabVoice = "upper tab" { \clef "moderntab" \voiceOne \upper }
       \context TabVoice = "lower tab" { \clef "moderntab" \voiceTwo \lower }
     >>
   >>
 
   \layout {
     \context {
       \Staff
-      \override StringNumber transparent = ##t
+      \override StringNumber.transparent = ##t
     }
     \context {
       \TabStaff
-      \revert Arpeggio stencil
+      \revert Arpeggio.stencil
     }
   }
 }