Merge branch '2.3' into 2.7

* 2.3:
  Updated all the README files
  [TwigBundle] Fix failing test on appveyor
  [FrameworkBundle] Fix a regression in handling absolute and namespaced template paths
  Allow to normalize \Traversable
  Remove _path from query parameters when fragment is a subrequest and request attributes are already set Added tests for _path removal in FragmentListener
  Simplified everything
  Added a test
  Fixed the problem in an easier way
  Fixed a syntax issue
  Improved the error message when a template is not found
  [CodingStandards] Conformed to coding standards
  [TwigBundle] fixed Include file locations in "Template could not be found" exception

Author: fabpot

README.md

@@ -1,126 +1,16 @@
 Validator Component
 ===================
 
-This component is based on the JSR-303 Bean Validation specification and
-enables specifying validation rules for classes using XML, YAML, PHP or
-annotations, which can then be checked against instances of these classes.
-
-Usage
------
-
-The component provides "validation constraints", which are simple objects
-containing the rules for the validation. Let's validate a simple string
-as an example:
-
-```php
-use Symfony\Component\Validator\Validation;
-use Symfony\Component\Validator\Constraints\Length;
-
-$validator = Validation::createValidator();
-
-$violations = $validator->validate('Bernhard', new Length(array('min' => 10)));
-```
-
-This validation will fail because the given string is shorter than ten
-characters. The precise errors, here called "constraint violations",  are
-returned by the validator. You can analyze these or return them to the user.
-If the violation list is empty, validation succeeded.
-
-Validation of arrays is possible using the `Collection` constraint:
-
-```php
-use Symfony\Component\Validator\Validation;
-use Symfony\Component\Validator\Constraints as Assert;
-
-$validator = Validation::createValidator();
-
-$constraint = new Assert\Collection(array(
-    'name' => new Assert\Collection(array(
-        'first_name' => new Assert\Length(array('min' => 101)),
-        'last_name' => new Assert\Length(array('min' => 1)),
-    )),
-    'email' => new Assert\Email(),
-    'simple' => new Assert\Length(array('min' => 102)),
-    'gender' => new Assert\Choice(array(3, 4)),
-    'file' => new Assert\File(),
-    'password' => new Assert\Length(array('min' => 60)),
-));
-
-$violations = $validator->validate($input, $constraint);
-```
-
-Again, the validator returns the list of violations.
-
-Validation of objects is possible using "constraint mapping". With such
-a mapping you can put constraints onto properties and objects of classes.
-Whenever an object of this class is validated, its properties and
-method results are matched against the constraints.
-
-```php
-use Symfony\Component\Validator\Validation;
-use Symfony\Component\Validator\Constraints as Assert;
-
-class User
-{
-    /**
-     * @Assert\Length(min = 3)
-     * @Assert\NotBlank
-     */
-    private $name;
-
-    /**
-     * @Assert\Email
-     * @Assert\NotBlank
-     */
-    private $email;
-
-    public function __construct($name, $email)
-    {
-        $this->name = $name;
-        $this->email = $email;
-    }
-
-    /**
-     * @Assert\IsTrue(message = "The user should have a Google Mail account")
-     */
-    public function isGmailUser()
-    {
-        return false !== strpos($this->email, '@gmail.com');
-    }
-}
-
-$validator = Validation::createValidatorBuilder()
-    ->enableAnnotationMapping()
-    ->getValidator();
-
-$user = new User('John Doe', '[email protected]');
-
-$violations = $validator->validate($user);
-```
-
-This example uses the annotation support of Doctrine Common to
-map constraints to properties and methods. You can also map constraints
-using XML, YAML or plain PHP, if you dislike annotations or don't want
-to include Doctrine. Check the documentation for more information about
-these drivers.
+The Validator component provides tools to validate values following the
+[JSR-303 Bean Validation specification][1].
 
 Resources
 ---------
 
-Silex integration:
-
-https://github.com/silexphp/Silex/blob/master/src/Silex/Provider/ValidatorServiceProvider.php
-
-Documentation:
-
-https://symfony.com/doc/2.7/book/validation.html
-
-JSR-303 Specification:
-
-http://jcp.org/en/jsr/detail?id=303
-
-You can run the unit tests with the following command:
+  * [Documentation](https://symfony.com/doc/current/book/validation.html)
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)
 
-    $ cd path/to/Symfony/Component/Validator/
-    $ composer install
-    $ phpunit
+[1]: http://jcp.org/en/jsr/detail?id=303