Add imagedestroy to save method

Author: petrwl

lib/ImageResize.php

@@ -200,6 +200,8 @@ public function save($filename, $image_type = null, $quality = null, $permission
         if ($permissions) {
             chmod($filename, $permissions);
         }
+        
+        imagedestroy($dest_image);
 
         return $this;
     }