added PR #309 dump panel

[simialbi]

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	❌
Tests pass?	✔️
Fixed issues	PR #309, #247

Working demo: http://demo.karlen.li/web/

Debug calling controller code:

    /**
     * Displays homepage.
     *
     * @return string
     */
    public function actionIndex()
    {
        Yii::debug([
            'test' => 'value',
            'foo' => 'bar',
            'bar' => 'baz'
        ]);
        Yii::debug(null);
        $std = new \stdClass();
        $std->null = null;
        $std->test = 'value';
        $std->integer = 22;
        $std->float = 3.2521553;
        $std->boolean = false;
        $std->array = [
            'test' => 'value',
            'foo' => 'bar',
            'null' => null,
            'integer' => 33,
            'float' => 3.2521553,
            'boolean' => false
        ];
        Yii::debug($std);

        return $this->render('index');
    }

[samdark]

Merged. Thanks!