- Chg #4911: Changed callback signature used in `yii\base\ArrayableTrait::fields()` from `function ($field, $model) {` to `function ($model, $field) {` (samdark)
- Chg #4955: Replaced callbacks with events for `ActiveForm` (qiangxue)
- Removed `beforeValidate()`, `beforeValidateAll()`, `afterValidate()`, `afterValidateAll()`, `ajaxBeforeSend()` and `ajaxComplete()` from `ActiveForm`.
- Added `beforeValidate`, `afterValidate`, `beforeSubmit`, `ajaxBeforeSend` and `ajaxComplete` events to `yii.activeForm`.
- Added `beforeValidate`, `afterValidate`, `beforeValidateAttribute`, `afterValidateAttribute`, `beforeSubmit`, `ajaxBeforeSend` and `ajaxComplete` events to `yii.activeForm` jQuery plugin.
- Chg: Replaced `clearAll()` and `clearAllAssignments()` in `yii\rbac\ManagerInterface` with `removeAll()`, `removeAllRoles()`, `removeAllPermissions()`, `removeAllRules()` and `removeAllAssignments()` (qiangxue)
- Chg: Added `$user` as the first parameter of `yii\rbac\Rule::execute()` (qiangxue)
- Chg: `yii\grid\DataColumn::getDataCellValue()` visibility is now `public` to allow accessing the value from a GridView directly (cebe)