Enabling new Rubocop checks

[skalee]

Plenty of new code style checks have been added to Rubocop:

A detailed list

Lint/DuplicateBranch: # (new in 1.3)
  Enabled: true
Lint/DuplicateRegexpCharacterClassElement: # (new in 1.1)
  Enabled: true
Lint/EmptyBlock: # (new in 1.1)
  Enabled: true
Lint/EmptyClass: # (new in 1.3)
  Enabled: true
Lint/NoReturnInBeginEndBlocks: # (new in 1.2)
  Enabled: true
Lint/ToEnumArguments: # (new in 1.1)
  Enabled: true
Lint/UnexpectedBlockArity: # (new in 1.5)
  Enabled: true
Lint/UnmodifiedReduceAccumulator: # (new in 1.1)
  Enabled: true
Style/ArgumentsForwarding: # (new in 1.1)
  Enabled: true
Style/CollectionCompact: # (new in 1.2)
  Enabled: true
Style/DocumentDynamicEvalDefinition: # (new in 1.1)
  Enabled: true
Style/NegatedIfElseCondition: # (new in 1.2)
  Enabled: true
Style/NilLambda: # (new in 1.3)
  Enabled: true
Style/RedundantArgument: # (new in 1.4)
  Enabled: true
Style/SwapValues: # (new in 1.1)
  Enabled: true
Performance/AncestorsInclude: # (new in 1.7)
  Enabled: true
Performance/BigDecimalWithNumericArgument: # (new in 1.7)
  Enabled: true
Performance/BlockGivenWithExplicitBlock: # (new in 1.9)
  Enabled: true
Performance/CollectionLiteralInLoop: # (new in 1.8)
  Enabled: true
Performance/ConstantRegexp: # (new in 1.9)
  Enabled: true
Performance/MethodObjectAsBlock: # (new in 1.9)
  Enabled: true
Performance/RedundantEqualityComparisonBlock: # (new in 1.10)
  Enabled: true
Performance/RedundantSortBlock: # (new in 1.7)
  Enabled: true
Performance/RedundantSplitRegexpArgument: # (new in 1.10)
  Enabled: true
Performance/RedundantStringChars: # (new in 1.7)
  Enabled: true
Performance/ReverseFirst: # (new in 1.7)
  Enabled: true
Performance/SortReverse: # (new in 1.7)
  Enabled: true
Performance/Squeeze: # (new in 1.7)
  Enabled: true
Performance/StringInclude: # (new in 1.7)
  Enabled: true
Performance/Sum: # (new in 1.8)
  Enabled: true

I want to enable checks at least from the Lint department, as they are typically very good in detecting code smells. Regarding other new checks, I can either enable all of them or some of them or just silence warnings about these new checks.

More details: https://docs.rubocop.org/rubocop/versioning.html.