v1.0.0

The new bnf environment provides a more flexible environment to typeset BNF grammars, without sacrificing the simple DSL used for the (now deprecated) bnfgrammar environment.

This new version provides

1. a DSL more tolerable than the previous version, e.g., it now accepts trailing delimiters (;;), leading alternative delimiter (|), etc;
2. flexible configuration, e.g., custom delimiters and symbols;
3. more helpful error/warning messages;
4. the backend as the tabularray package; and
5. (hopefully) a more descriptive manual.