(lloc_default): New function, which handles

(lloc_default): New function, which handles
empty locations more accurately.
(YYLLOC_DEFAULT): Use it.
(%token COLON): Remove.
(%token ID_COLON): New token.
(rules): Use it.
(declarations, rules): Remove trailing semicolon.
(declaration, rules_or_grammar_declaration):
Allow empty (";") declaration.
(symbol_def): Remove empty actions; no longer needed.
(rules_or_grammar_declaration): Remove trailing semicolon.
(semi_colon.opt): Remove.