* src/parse-gram.y: Include quotearg.h.

* src/parse-gram.y: Include quotearg.h.
(string_as_id): Quote $1 before using it as a key, since the
lexer no longer quotes it for us.
(string_content): Don't strip quotes, since lexer no longer
quotes it for us.
* src/scan-gram.l: Include quotearg.h.
("\""): Omit quote.
("'"<SC_ESCAPED_CHARACTER>): Quote symbol before using it as
a key, since the rest of the lexer doesn't quote it.
* src/symtab.c (symbol_get): Don't quote symbol; caller does it now.
* tests/regression.at (Token definitions): Check for backslashes
in token strings.