cs: Switch to a stricter way of coding - this might break in a lot of places.

src/Bundle/ChillBudgetBundle/Entity/AbstractElement.php

@@ -7,6 +7,15 @@
  * the LICENSE file that was distributed with this source code.
  */
 
+declare(strict_types=1);
+
+/**
+ * Chill is a software for social workers.
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
 namespace Chill\AMLI\BudgetBundle\Entity;
 
 use Chill\PersonBundle\Entity\Person;
@@ -136,7 +145,7 @@ abstract class AbstractElement
 
     public function isEmpty()
     {
-        return 0 == $this->amount;
+        return 0 === $this->amount;
     }
 
     abstract public function isResource(): bool;