for prev, next, first and last page.
http://www.w3.org/TR/html401/struct/links.html#h-12.1.2

SELECT DISTINCT queries made subqueries in Query::queryScalar 

Use the current appliaction language in DatePicker

Changed `Controller::afterAction()`, `Module::afterAction()` and `ActionFilter::afterAction()` to pass `$result` by value instead of reference

added server name, for creating url rules

Change AssetBundle.register() return type to static

Enable IDE typehints for custom AssetBundle properties (related to #2572).

Fix https://github.com/yiisoft/yii2/issues/2562

Fixed typos

call hasMethod() instead of using method_exists

Fix for #2549

Fixed typo in runWithParams

Typo fixes for $user->attributes

print_r($data) should be print_r($user->attributes)

first draft of the extension generator