Merge branch '2.3' into 2.7

* 2.3:
  typofix - https://github.com/vlajos/misspell_fixer
  [Yaml] Nested merge keys
  Add support for variadic arguments in the GetSetNormalizer

Conflicts:
	src/Symfony/Component/Serializer/Normalizer/GetSetMethodNormalizer.php
	src/Symfony/Component/Serializer/Tests/Normalizer/GetSetMethodNormalizerTest.php
	src/Symfony/Component/Validator/Tests/Mapping/ClassMetadataTest.php
	src/Symfony/Component/Yaml/Tests/Fixtures/sfMergeKey.yml

Author: nicolas-grekas

CHANGELOG.md

@@ -14,7 +14,7 @@ CHANGELOG
 
  * Added 'host' option to firewall configuration
  * Added 'csrf_token_generator' and 'csrf_token_id' options to firewall logout
-   listener configuration to supercede/alias 'csrf_provider' and 'intention'
+   listener configuration to supersede/alias 'csrf_provider' and 'intention'
    respectively
  * Moved 'security.secure_random' service configuration to FrameworkBundle