bbatsov/rubocop

### New features

* [#5973](https://github.com/rubocop/rubocop/issues/5973): Add new `Style/IpAddresses` cop. ([@dvandersluis][])
* [#5843](https://github.com/rubocop/rubocop/issues/5843): Add configuration options to `Naming/MemoizedInstanceVariableName` cop to allow leading underscores. ([@leklund][])
* [#5843](https://github.com/rubocop/rubocop/issues/5843): Add `EnforcedStyleForLeadingUnderscores` to `Naming/MemoizedInstanceVariableName` cop to allow leading underscores. ([@leklund][])
* `Performance/Sample` will now register an offense when using `shuffle` followed by `at` or `slice`. ([@rrosenblum][])

### Bug fixes

* [#5987](https://github.com/rubocop/rubocop/issues/5987): Suppress errors when using ERB template in Rails/BulkChangeTable. ([@wata727][])
* [#4878](https://github.com/rubocop/rubocop/issues/4878): Fix false positive in `Layout/IndentationWidth` when multiple modifiers and def are on the same line. ([@tatsuyafw][])
* [#5966](https://github.com/rubocop/rubocop/issues/5966): Fix a false positive for `Layout/ClosingHeredocIndentation` when heredoc content is outdented compared to the closing. ([@koic][])
* Fix auto-correct support check for custom cops on --auto-gen-config. ([@r7kamura][])
* Fix exception that occurs when auto-correcting a modifier if statement in `Style/UnneededCondition`. ([@rrosenblum][])
* [#6025](https://github.com/rubocop/rubocop/pull/6025): Fix an incorrect auto-correct for `Lint/UnneededCondition` when using if_branch in `else` branch. ([@koic][])
* [#6029](https://github.com/rubocop/rubocop/issues/6029): Fix a false positive for `Lint/ShadowedArgument` when reassigning to splat variable. ([@koic][])
* [#6035](https://github.com/rubocop/rubocop/issues/6035): Fix error on autocorrection when `Layout/LeadingBlankLines` is the first cop to act. ([@Vasfed][])
* [#6036](https://github.com/rubocop/rubocop/issues/6036): Make `Rails/BulkChangeTable` aware of string table name. ([@wata727][])
* [#5467](https://github.com/rubocop/rubocop/issues/5467): Fix a false negative for `Style/MultipleComparison` when multiple comparison is not part of a conditional. ([@koic][])
* [#6042](https://github.com/rubocop/rubocop/pull/6042): Fix `Lint/RedundantWithObject` error on missing parameter to `each_with_object`. ([@Vasfed][])
* [#6056](https://github.com/rubocop/rubocop/pull/6056): Support string timestamps in `Rails/CreateTableWithTimestamps` cop. ([@drn][])
* [#6052](https://github.com/rubocop/rubocop/issues/6052): Fix a false positive for `Style/SymbolProc` when using  block with adding a comma after the sole argument. ([@koic][])
* [#2743](https://github.com/rubocop/rubocop/issues/2743): Support `<<` as a kind of assignment operator in `Layout/EndAlignment`. ([@jonas054][])
* [#6067](https://github.com/rubocop/rubocop/issues/6067): Prevent auto-correct error for `Performance/InefficientHashSearch` when a method by itself and `include?` method are method chaining. ([@koic][])

### Changes

* [#6006](https://github.com/rubocop/rubocop/pull/6006): Remove `rake repl` task. ([@koic][])
* [#5990](https://github.com/rubocop/rubocop/pull/5990): Drop support for MRI 2.1. ([@drenmi][])
* [#3299](https://github.com/rubocop/rubocop/issues/3299): `Lint/UselessAccessModifier` now warns when `private_class_method` is used without arguments. ([@Darhazer][])
* [#6026](https://github.com/rubocop/rubocop/pull/6026): Exclude `refine` by default from `Metrics/BlockLength` cop. ([@kddeisz][])
* [#4882](https://github.com/rubocop/rubocop/issues/4882): Use `IndentationWidth` of `Layout/Tab` for other cops. ([@AlexWayfer][])

[@dvandersluis]: https://github.com/dvandersluis
[@leklund]: https://github.com/leklund
[@rrosenblum]: https://github.com/rrosenblum
[@wata727]: https://github.com/wata727
[@tatsuyafw]: https://github.com/tatsuyafw
[@koic]: https://github.com/koic
[@r7kamura]: https://github.com/r7kamura
[@Vasfed]: https://github.com/Vasfed
[@drn]: https://github.com/drn
[@jonas054]: https://github.com/jonas054
[@drenmi]: https://github.com/drenmi
[@Darhazer]: https://github.com/Darhazer
[@kddeisz]: https://github.com/kddeisz
[@AlexWayfer]: https://github.com/AlexWayfer