Make arguments like Context.GrobName accessible as symbol lists

Documentation/snippets/new/glissandi-can-skip-grobs.ly

-\version "2.17.5"
+\version "2.17.6"
 
 \header {
   lsrtags = "expressive-marks, staff-notation, tweaks-and-overrides"
   doctitle = "Glissandi can skip grobs"
   texidoc = "@code{NoteColumn} grobs can be skipped over by glissandi."
 }
 
 \relative c' {
   a2 \glissando
-  \once \override NoteColumn glissando-skip = ##t
+  \once \override NoteColumn.glissando-skip = ##t
   f''4 d,
 }