* src/reader.h, src/reader.c (symbol_list_new): Export it.

* src/reader.h, src/reader.c (symbol_list_new): Export it.
(symbol_list_prepend): New.
* src/parse-gram.y (%union): `list' is a new member.
(symbols.1): New, replaces...
(terms_to_prec.1, nterms_to_type.1): these.
* src/symtab.h, src/symtab.c (symbol_type_set, symbol_precedence_set)
Take a location as additional argument.
Adjust all callers.