%define: accept unquoted values.

* NEWS (2.5): Group all %define changes together, and document
this one.  Remove quotes in IELR and canonical LR entry.
* doc/bison.texinfo: Remove quotes in most examples throughout.
(Decl Summary): Update %define documentation.
(Table of Symbols): Likewise.
* src/ielr.c (LrType): Update documentation.
* src/parse-gram.y (content.opt): Add production for ID.
* tests/actions.at: Remove quotes in most tests.
* tests/calc.at: Likewise.
* tests/existing.at: Likewise.
* tests/input.at: Likewise.
* tests/local.at: Likewise.
* tests/push.at: Likewise.
* tests/reduce.at: Likewise.
* tests/torture.at: Likewise.

src/parse-gram.y

@@ -563,6 +563,7 @@ variable:
 /* Some content or empty by default. */
 content.opt:
   /* Nothing. */   { $$ = ""; }
+| ID { $$ = $1; }
 | STRING
 ;