Events `beforeFilter.yiiGridView` and `afterFilter.yiiGridView` javascript events created for advanced use cases.

Trigger a new `filter.yiiGridView` event for yii grid view after grid filters are applied. This will enable developer to code a lot of use cases based on the grid filtering event. The filter `$form` can be accessed as a parameter to the event.

If you don't want to install command-line utils globally, you have to specify it's paths.

    public $commands = [
        'styl' => ['css', '@app/node_modules/bin/stylus < {from} > {to}'],
    ];

close #5130

- in composer the `~` operator is just a shortcut for `~1.0` = `>=1.0.0,<2.0.0`
  it does not prevent dev versions to be installed but neither does `1.*`
- dev versions are constrolled via `minimum-stability` setting and the
  `@dev`, `@beta`, `@stable`,... settings.
- setting bower packages that ship compiled files only with the stable
  release to use `@stable` in composer.json of the applictaions. This
  setting can be removed when we remove the `minimum-stability=dev`
  setting after GA.

Translate spanish docs

fixes #5119

fixes #5104, fixes #5101

Fixes #2380: Added `yii\widgets\ActiveForm::enableClientScript` to support turning on and off client side script generation

Fixes #5058: `yii\helpers\Html::activeCheckbox()` and `activeRadio()` will generate labels by default using the corresponding attribute labels

Asset improvements

[skip ci] Russian translation of structure-views.md

Formatting fix

Phew :)

[ci skip] Update structure-views.md

- We do not generate static pages in controllers, but merely output them.
- We need to say that the data is needed to be plainly put into the view, as the reader might expect something more sophisticated to happen here.

Update structure-views.md

registerMetaTag() usage clarification

Fixed `yii\console\controllers\CacheController` does not check if cache component instance of 'yii\caching\Cache'

close #5055

[WIP] extracted date format converting to a helper class