Merge branch '2.3' into 2.7

* 2.3:
  [travis] timeout the sigchild tests at 60s
  CS: Single line comments should use double slashes (//) and not hash (#).
  Do not use HttpKernel Extension when not needed
  bumped Symfony version to 2.3.37
  updated VERSION for 2.3.36
  update CONTRIBUTORS for 2.3.36
  updated CHANGELOG for 2.3.36
  use nowdoc instead of heredoc

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php
	src/Symfony/Bundle/FrameworkBundle/Command/RouterApacheDumperCommand.php
	src/Symfony/Bundle/FrameworkBundle/Command/RouterMatchCommand.php
	src/Symfony/Bundle/FrameworkBundle/Translation/Translator.php
	src/Symfony/Bundle/TwigBundle/Command/LintCommand.php
	src/Symfony/Component/Config/Tests/Definition/Dumper/YamlReferenceDumperTest.php
	src/Symfony/Component/Debug/ExceptionHandler.php
	src/Symfony/Component/HttpKernel/Kernel.php
	src/Symfony/Component/Routing/Generator/Dumper/PhpGeneratorDumper.php

Author: nicolas-grekas

Command/AssetsInstallCommand.php

@@ -38,7 +38,7 @@ protected function configure()
             ->addOption('symlink', null, InputOption::VALUE_NONE, 'Symlinks the assets instead of copying it')
             ->addOption('relative', null, InputOption::VALUE_NONE, 'Make relative symlinks')
             ->setDescription('Installs bundles web assets under a public web directory')
-            ->setHelp(<<<EOT
+            ->setHelp(<<<'EOT'
 The <info>%command.name%</info> command installs bundle assets into a given
 directory (e.g. the <comment>web</comment> directory).
 

Command/CacheClearCommand.php

@@ -37,7 +37,7 @@ protected function configure()
                 new InputOption('no-optional-warmers', '', InputOption::VALUE_NONE, 'Skip optional cache warmers (faster)'),
             ))
             ->setDescription('Clears the cache')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command clears the application cache for a given environment
 and debug mode:
 

Command/CacheWarmupCommand.php

@@ -33,7 +33,7 @@ protected function configure()
                 new InputOption('no-optional-warmers', '', InputOption::VALUE_NONE, 'Skip optional cache warmers (faster)'),
             ))
             ->setDescription('Warms up an empty cache')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command warms up the cache.
 
 Before running this command, the cache must be empty.

Command/ConfigDumpReferenceCommand.php

@@ -40,7 +40,7 @@ protected function configure()
                 new InputOption('format', null, InputOption::VALUE_REQUIRED, 'The output format (yaml or xml)', 'yaml'),
             ))
             ->setDescription('Dumps the default configuration for an extension')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command dumps the default configuration for an
 extension/bundle.
 

Command/ContainerDebugCommand.php

@@ -54,7 +54,7 @@ protected function configure()
                 new InputOption('raw', null, InputOption::VALUE_NONE, 'To output raw description'),
             ))
             ->setDescription('Displays current services for an application')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command displays all configured <comment>public</comment> services:
 
   <info>php %command.full_name%</info>

Command/RouterApacheDumperCommand.php

@@ -57,7 +57,7 @@ protected function configure()
                 new InputOption('base-uri', null, InputOption::VALUE_REQUIRED, 'The base URI'),
             ))
             ->setDescription('[DEPRECATED] Dumps all routes as Apache rewrite rules')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> dumps all routes as Apache rewrite rules.
 These can then be used with the ApacheUrlMatcher to use Apache for route
 matching.

Command/RouterDebugCommand.php

@@ -60,7 +60,7 @@ protected function configure()
                 new InputOption('raw', null, InputOption::VALUE_NONE, 'To output raw route(s)'),
             ))
             ->setDescription('Displays current routes for an application')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> displays the configured routes:
 
   <info>php %command.full_name%</info>

Command/RouterMatchCommand.php

@@ -56,7 +56,7 @@ protected function configure()
                 new InputOption('host', null, InputOption::VALUE_REQUIRED, 'Sets the URI host'),
             ))
             ->setDescription('Helps debug routes by simulating a path info match')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> shows which routes match a given request and which don't and for what reason:
 
   <info>php %command.full_name% /foo</info>

Command/ServerRunCommand.php

@@ -38,7 +38,7 @@ protected function configure()
             ))
             ->setName('server:run')
             ->setDescription('Runs PHP built-in web server')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> runs PHP built-in web server:
 
   <info>%command.full_name%</info>

Command/TranslationUpdateCommand.php

@@ -45,7 +45,7 @@ protected function configure()
                 new InputOption('clean', null, InputOption::VALUE_NONE, 'Should clean not found messages'),
             ))
             ->setDescription('Updates the translation file')
-            ->setHelp(<<<EOF
+            ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command extract translation strings from templates
 of a given bundle or the app folder. It can display them or merge the new ones into the translation files.
 When new translation strings are found it can automatically add a prefix to the translation