v0.11.0

• Fix false positive in ReturnTypeDeclarationSniff with nullable types.
• Relax check for missing return type when {aType}|null doc bloc is present.
• Add is to the list of allowed short names.
• Added FunctionBodyStartSniff to deal with blank lines on top of functions body.
• Added VariablesNameSniff.
• Improved PhpcsHelpers::variableIsProperty().
• Improved failure handling in FixturesTest.
• Use NeutronStandard by opting-in rules instead of opting-out
• Properly handle Generators and return types.