Make arguments like Context.GrobName accessible as symbol lists

Documentation/snippets/changing-the-breath-mark-symbol.ly

 %% DO NOT EDIT this file manually; it is automatically
 %% generated from LSR http://lsr.dsi.unimi.it
 %% Make any changes in LSR itself, or in Documentation/snippets/new/ ,
 %% and then run scripts/auxiliar/makelsr.py
 %%
 %% This file is in the public domain.
-\version "2.16.0"
+\version "2.17.6"
 
 \header {
   lsrtags = "expressive-marks"
 
   texidoc = "
 The glyph of the breath mark can be tuned by overriding the @code{text}
 property of the @code{BreathingSign} layout object with any markup
 text.
 
 "
   doctitle = "Changing the breath mark symbol"
 } % begin verbatim
 
 \relative c'' {
   c2
-  \override BreathingSign #'text =
+  \override BreathingSign.text =
     \markup { \musicglyph #"scripts.rvarcomma" }
   \breathe
   d2
 }