Merge branch '4.1' into 4.2

* 4.1:
  bump required Twig version
  fix compatibility with Twig >= 2.6.1
  [Form] SA fix
  fix compatibility with PHPUnit 4.8
  remove return type hint for PHP 5 compatibility
  SCA: minor code tweaks
  Component CssSelector tests
  [DebugClassLoader] Readd findFile() method
  [Console] Fix composer.json suggest/provide
  Revert "bug #29597 [DI] fix reporting bindings on overriden services as unused (nicolas-grekas)"
  Fixed exception wording
  Fix SwiftMailerHandler to support Monolog's latest reset functionality

Author: fabpot

ContainerConstraintValidatorFactory.php

@@ -28,7 +28,7 @@ class ContainerConstraintValidatorFactory implements ConstraintValidatorFactoryI
     public function __construct(ContainerInterface $container)
     {
         $this->container = $container;
-        $this->validators = array();
+        $this->validators = [];
     }
 
     /**
@@ -46,7 +46,7 @@ public function getInstance(Constraint $constraint)
                 $this->validators[$name] = $this->container->get($name);
             } else {
                 if (!class_exists($name)) {
-                    throw new ValidatorException(sprintf('Constraint validator "%s" does not exist or it is not enabled. Check the "validatedBy" method in your constraint class "%s".', $name, \get_class($constraint)));
+                    throw new ValidatorException(sprintf('Constraint validator "%s" does not exist or is not enabled. Check the "validatedBy" method in your constraint class "%s".', $name, \get_class($constraint)));
                 }
 
                 $this->validators[$name] = new $name();