Fixes #1654: Fixed the issue that a new message source object is generated for every new message being translated

The signature for `yii\gridview\ActionColumn::urlCreator` is changed - the `$action` parameter is moved to the first

Fixes #1610: `Html::activeCheckboxList()` and `Html::activeRadioList()` will submit an empty string if no checkbox/radio is selected

Fixes #1499: Added `ActionColumn::controller` property to support customizing the controller for handling GridView actions

Renamed `attributeName` and `className` to `targetAttribute` and `targetClass` for `UniqueValidator` and `ExistValidator`.
Refactored UniqueValidator and ExistValidator.

Fixes #1597: Added `enableAutoLogin` to basic and advanced application templates so "remember me" now works properly

Fixes #1579: throw exception when the given AR relation name does not match in a case sensitive manner.
Renamed `ActiveRecord::getPopulatedRelations()` to `getRelatedRecords()`

fixes #1545

issue #1523