[Filters] [Config] [DI] Add Filter configuration class as public service

Config/Filter/Type/Background.php

@@ -43,9 +43,9 @@ final class Background implements FilterInterface
 
     /**
      * @param string      $name
-     * @param string|null $color
-     * @param string|null $transparency
-     * @param string|null $position
+     * @param string|null $color        background color HEX value
+     * @param string|null $transparency possible values 0..100
+     * @param string|null $position     position of the input image on the newly created background image. Valid values: topleft, top, topright, left, center, right, bottomleft, bottom, and bottomright
      * @param Size        $size
      */
     public function __construct(

Factory/Config/StackFactory.php

@@ -11,15 +11,16 @@
 
 namespace Liip\ImagineBundle\Factory\Config;
 
+use Liip\ImagineBundle\Config\FilterInterface;
 use Liip\ImagineBundle\Config\Stack;
 
 class StackFactory
 {
     /**
-     * @param string      $name
-     * @param string|null $dataLoader
-     * @param int|null    $quality
-     * @param array       $filters
+     * @param string            $name
+     * @param string|null       $dataLoader
+     * @param int|null          $quality
+     * @param FilterInterface[] $filters
      *
      * @return Stack
      */