Tatsu

* Fix walker cache logic in ``NodeWalker`` (by-Exist)

- Fix pickling of AST. The change also affects parsing within multiprocessing (fizbin)
- Fall back to `repr()` for types not handled by `json`(dnicolodi)
- Ensure there is exactly one method cache per Walker class
- Bug fixes, upgrades, and improvements by (dnicolodi)

- Make sure that the generated parser is the same as the bootstrap
parser.
- Honor grouping in pattern expressions with the semantics of
`re.findall(pattern, text)[0]`. Now groups that should not be
returned when parsing should use the `(?:)` syntax. Now patterns
align with [Python](http://python.org) `re` independently of the
`ignorecase` setting for the grammar.
- Allow `{}` interpolation in `` `constant ``[ expressions with the
semantics of ]{.title-ref}[str.format()]{.title-ref}\`
- Add ``[constant]{.title-ref}`` as a multiline version of
`` `constant ``\`.
- Add \^``[constant]{.title-ref}`` and \^`` `constant ``[ as syntax
for an \`alert]{.title-ref} expression. Alerts produce no tokens bug
get registed in [parseinfo]{.title-ref} records.
- BUG: make the `->` skip expression always stop at EOF.
- Make the `->` skip expression go over comments, and not log while
skipping.
- Patch problem with pickling `FailedCut` while running parsing in
parallel.
- Optimize model pickling and parallel processing to reduce runtime
and memory use with `parproc`
- Add a representation of `~` cut expressions to parse traces

- Fix that settings passed to `Context.parse()` were ignored. Add `Context.active_config` for the configuration active during a parse
- Define `Node._parent` as part of the `dataclass`

- Make `AST` and `Node` hashable. Necessary for caching `Node.children()`
- Implement `Node.__eq__()` in terms of identity or `Node.ast.__eq__()__`
- Fix regression in which rule order is lost in generated parsers ([dtrckd](https://github.com/dtrckd))
- Restore `Node.ast` (was removed because of problems with `__eq__()`)
- Get `Node.children()` from `Node.ast` when there are no attributes defined for the `Node`. This restores the desired behavior while developing a parse model.