Merge branch '3.4' into 4.0

* 3.4:
  Clean up
  Update return type in docblock.
  PHP CS Fixer: no need to exclude xml and yml files
  PHP CS Fixer: no need to exclude json file
  Update LICENSE year... forever
  fixed some deprecation messages
  fixed CS
  Fixes for Oracle in PdoSessionHandler
  fixed some deprecation messages
  fixed some deprecation messages
  fixed some deprecation messages
  fixed some deprecation messages
  [TwigBundle/Brige] catch missing requirements to throw meaningful exceptions
  [HttpKernel] Call Response->setPrivate() instead of sending raw header() when session is started
  [FrameworkBundle] Make cache:clear "atomic" and consistent with cache:warmup
  Suggest to write an implementation if the interface cannot be autowired
  [Debug] Skip DebugClassLoader checks for already parsed files
  [2.7][DX] Use constant message contextualisation for deprecations
  Remove group options without data and fix normalization
  Remove redundant translation path

Author: nicolas-grekas

CHANGELOG.md

@@ -31,7 +31,7 @@ CHANGELOG
  * deprecated OptionsResolver::isKnown() in favor of isDefined()
  * [BC BREAK] OptionsResolver::isRequired() returns true now if a required
    option has a default value set
- * [BC BREAK] merged Options into OptionsResolver and turned Options into an 
+ * [BC BREAK] merged Options into OptionsResolver and turned Options into an
    interface
  * deprecated Options::overload() (now in OptionsResolver)
  * deprecated Options::set() (now in OptionsResolver)
@@ -42,7 +42,7 @@ CHANGELOG
    lazy option/normalizer closures now
  * [BC BREAK] removed Traversable interface from Options since using within
    lazy option/normalizer closures resulted in exceptions
- * [BC BREAK] removed Options::all() since using within lazy option/normalizer 
+ * [BC BREAK] removed Options::all() since using within lazy option/normalizer
    closures resulted in exceptions
  * [BC BREAK] OptionDefinitionException now extends LogicException instead of
    RuntimeException

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2004-2017 Fabien Potencier
+Copyright (c) 2004-present Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal