docs

docs.

add ErrInto trait for more error conversion options.

remove when(). dubios utility.
move context::* to tracker.
remove Hints::Needed.

remove ParserError::expected_grouped_by* and ParserError::suggested_grouped_by*. The don't work with non-LocatedSpan types, so they are to weak.

remove SpanLocation. Doesn't work for non-LocatedSpan, so it's to weak.

clippy

remove parser_error but use it's impl as error_code.

change conditional according to the rest.

toml error