New alist to replace special characters.

lily/lexer.ll

 %{ // -*-Fundamental-*-
 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1996--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
                  Jan Nieuwenhuizen <janneke@gnu.org>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
@@ skipping 115 matching lines @@
 %x sourcefilename
 %x version
 
 A               [a-zA-Z\200-\377]
 AA              {A}|_
 N               [0-9]
 AN              {AA}|{N}
 ANY_CHAR        (.|\n)
 PUNCT           [?!:'`]
 ACCENT          \\[`'"^]
+SPECIAL_CHAR            [&@]
 NATIONAL        [\001-\006\021-\027\031\036]
-TEX             {AA}|-|{PUNCT}|{ACCENT}|{NATIONAL}
+TEX             {AA}|-|{PUNCT}|{ACCENT}|{NATIONAL}|{SPECIAL_CHAR}
 DASHED_WORD             {A}({AN}|-)*
 DASHED_KEY_WORD         \\{DASHED_WORD}
 
 
 
 ALPHAWORD       {A}+
 UNSIGNED        {N}+
 E_UNSIGNED      \\{N}+
 FRACTION        {N}+\/{N}+
 INT             -?{UNSIGNED}
@@ skipping 898 matching lines @@
 {
    (void) yy_start_stack_ptr;
    (void) yy_start_stack_depth;
    (void) yy_start_stack;
    (void) yy_push_state;
    (void) yy_pop_state;
    (void) yy_top_state;
    (void) silence_lexer_warnings;
 }
 #endif