bbatsov/rubocop

### New features

* [#7737](https://github.com/rubocop/rubocop/issues/7737): Add new `Style/RedundantArgument` cop. ([@tejasbubane][])
* [#9064](https://github.com/rubocop/rubocop/issues/9064): Add `EmptyLineBetweenMethodDefs`, `EmptyLineBetweenClassDefs` and `EmptyLineBetweenModuleDefs` config options for `Layout/EmptyLineBetweenDefs` cop. ([@tejasbubane][])
* [#9043](https://github.com/rubocop/rubocop/pull/9043): Add `--stderr` to write all output to stderr except for the autocorrected source. ([@knu][])

### Bug fixes

* [#9067](https://github.com/rubocop/rubocop/pull/9067): Fix an incorrect auto-correct for `Lint::AmbiguousRegexpLiteral` when passing in a regexp to a method with no receiver. ([@amatsuda][])
* [#9060](https://github.com/rubocop/rubocop/issues/9060): Fix an error for `Layout/SpaceAroundMethodCallOperator` when using `__ENCODING__`. ([@koic][])
* [#7338](https://github.com/rubocop/rubocop/issues/7338): Handle assignment with `[]=` in `MultilineMethodCallIndentation`. ([@jonas054][])
* [#7726](https://github.com/rubocop/rubocop/issues/7726): Fix `MultilineMethodCallIndentation` indentation inside square brackets. ([@jonas054][])
* [#8857](https://github.com/rubocop/rubocop/issues/8857): Improve how `Exclude` properties are generated by `--auto-gen-config`. ([@jonas054][])

### Changes

* [#8788](https://github.com/rubocop/rubocop/issues/8788): Change `Style/Documentation` to not trigger offense with only macros. ([@tejasbubane][])
* [#8993](https://github.com/rubocop/rubocop/issues/8993): Allow `ExcludedMethods` config of `Metrics/MethodLength` cop to contain regex. ([@tejasbubane][])
* [#9073](https://github.com/rubocop/rubocop/issues/9073): Enable `Layout/LineLength`'s auto-correct by default. ([@bbatsov][])
* [#9079](https://github.com/rubocop/rubocop/pull/9079): Improve the gemspec to load only the necessary files without the git utility. ([@piotrmurach][])
* [#9059](https://github.com/rubocop/rubocop/pull/9059): Update `Lint/UnmodifiedReduceAccumulator` to accept blocks which return in the form `accumulator[element]`. ([@dvandersluis][])
* [#9072](https://github.com/rubocop/rubocop/pull/9072): `Lint/MissingSuper`: exclude `method_missing` and `respond_to_missing?`. ([@marcandre][])
* [#9074](https://github.com/rubocop/rubocop/pull/9074): Allow specifying a pull request ID when calling `rake changelog:*`. ([@marcandre][])

[@tejasbubane]: https://github.com/tejasbubane
[@knu]: https://github.com/knu
[@amatsuda]: https://github.com/amatsuda
[@koic]: https://github.com/koic
[@jonas054]: https://github.com/jonas054
[@bbatsov]: https://github.com/bbatsov
[@piotrmurach]: https://github.com/piotrmurach
[@dvandersluis]: https://github.com/dvandersluis
[@marcandre]: https://github.com/marcandre