close #7084

`yii\console\controllers\AssetController` now correctly handles relative image URLs if source and target CSS are under same directory

Fixes #6969: `yii\helpers\ArrayHelper::htmlEncode()` and `htmlDecode()` should not remove non-string data

Fixes #6697: Added `yii\helpers\Url::current()` method that allows adding or removing parameters from current URL

always use getConnection()

ensure PDO instance has been created at this point

always use unique directory for each test

http://en.wikipedia.org/wiki/Year_2038_problem

formatting date and time values for years >=2038 or <=1901 is now possible also with intl extension is
installed. 32bit systems will fall back to the PHP implementation because intl uses a 32bit UNIX timestamp internally.
On a 64bit system the intl formatter is used in all cases if installed.

fixes #5577

fixes #6748

Fixes #6398: Added support for specifying dependent component in terms of a configuration array for classes such as `DbCache`

fixes #6717

Fixes #6632: `yii\di\Container::get()` did not handle config parameter correctly when it is passed as a constructor parameter

fixed hhvm build.

Fixes #5494: Added support for specifying a menu header as a configuration array in `yii\bootstrap\Dropdown`

Fixes #5070: Gii controller generator should use controller class name instead of controller ID to specify new controller