in *parse_impl(); add support to the error handlers and their support
functions directly instead. There are simply too many APIs there that need
the translation to leave it to other code.
Add lex_error exception type, and add support for all the APIs that used to
take a parse_error param to now take either a parse_error or a lex_error.
Throw lex_error from failed parsing of lexed tokens in detail::make_token().
See #202.
underlying sequence, and change the way that the error handler is invoked, so
that it detects token iterators, and passes iterators into the underlying
range to the error handler, instead of the token iterators.
See #202.
parser_interface. token_spec is now a variable template that generates a
parser_interface wrapping a token_parser, which parameterized on the
token_spec_t. This way, a single token_spec use can be used to specify how to
lex, and how to parse.
See #202.
