Fixes #3240: Added support for assigning an anonymous function to `yii\widgets\ActiveForm::fieldConfig`
Update guide pt-BR README file
Translate guide/start-hello into pt-BR
Small fix in pt-br guide/README
Fixes #3738: ActiveField custom error selector not functioning
Fixes #2380: `yii\widgets\ActiveForm` will register validation js even if there are not fields inside
Merge pull request #4934 from alanwillms/pt_br_start_hello

[ci skip] pt-BR start-hello
Fixed test breaks.
Fixes #4288: added a hint on how to specify console boolean values to the output of help
Simplified ArrayTrait::fields() default implementation since it works fine w/ just field names as values
Better alias check
Removed unused variable initialization
added missing serbian translations
Fixed phpdoc
Fixed formatting, initialized options array
missing "." sign
Merge pull request #4937 from johonunu/missing-serbian-translations

[skip ci] Added more missing serbian translations
Reverted/fixed some incorrect changes.
Fixes #4936 [skip ci]
Fixes #2914: `ActiveForm::fieldConfig` will be merged recursively with the `$options` parameter in `ActiveForm::field()`