Ignore null value in comparison validators
Adapt security collector template name to webprofiler conventions
Merge branch '2.2' into 2.3

* 2.2:
  [Validator] fixed metadata serialization
  Fixed metadata serialization
Merge branch '2.3'

* 2.3:
  [Validator] fixed metadata serialization
  Fixed metadata serialization
[Intl] Updated stubs to reflect ICU 51.2
Merge branch '2.2' into 2.3

* 2.2:
  added trusted hosts check

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
Merge branch '2.3'

* 2.3:
  added trusted hosts check
updated CHANGELOG for 2.3.3
updated VERSION for 2.3.3
bumped Symfony version to 2.3.4-DEV
[HttpFoundation] added missing support for the new output API in PHP 5.4+
merged branch bschussek/icu51 (PR #8680)

This PR was merged into the 2.3 branch.

Discussion
----------

[Intl] Updated stubs to reflect ICU 51.2

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

In addition to the upgrade of the ICU component to ICU 51.2, this PR upgrades the stub classes to behave like their C counterparts do with ICU 51.2.

Commits
-------

8fa0453 [Intl] Updated stubs to reflect ICU 51.2
merged branch hacfi/security_profiler_tpl (PR #8673)

This PR was merged into the master branch.

Discussion
----------

Adapt security collector template name to webprofiler conventions

| Q             | A
| ------------- | ---
| Bug fix?      | no, but syntax consistency & future compatibility(?)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | fabpot/Twig#1156 which was reverted but will be merged in the future
| License       | MIT

Use Twig namespace syntax instead of bundle syntax for security webprofiler template to be consistent with @WebProfiler template names.

Commits
-------

66c792b Adapt security collector template name to webprofiler conventions
merged branch iteman/support_for_php_new_output_api (PR #8692)

This PR was merged into the master branch.

Discussion
----------

[HttpFoundation] add missing support for the new output API in PHP 5.4...

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

As of PHP 5.4, the new output API has been introduced:

* https://github.com/php/php-src/blob/master/README.NEW-OUTPUT-API
* https://github.com/php/php-src/commit/11d24c1593d6617f73d3f290617bd8994182f4dc
* https://bugs.php.net/bug.php?id=64977

Commits
-------

188c0ce [HttpFoundation] added missing support for the new output API in PHP 5.4+
Merge branch '2.2' into 2.3

* 2.2:
  added missing support for the new output API in PHP 5.4+
  Fixed bug introduced in #8675
  made the filesystem loader compatible with Twig 2.0
  bumped Symfony version to 2.2.6
  updated VERSION for 2.2.5
  update CONTRIBUTORS for 2.2.5
  updated CHANGELOG for 2.2.5
  replaced deprecated Twig features

Conflicts:
	src/Symfony/Bridge/Twig/Extension/FormExtension.php
	src/Symfony/Bridge/Twig/Extension/RoutingExtension.php
	src/Symfony/Component/HttpKernel/Kernel.php
Merge branch '2.3'

* 2.3:
  added missing support for the new output API in PHP 5.4+
  Fixed bug introduced in #8675
  made the filesystem loader compatible with Twig 2.0
  bumped Symfony version to 2.3.4-DEV
  updated VERSION for 2.3.3
  updated CHANGELOG for 2.3.3
  bumped Symfony version to 2.2.6
  updated VERSION for 2.2.5
  update CONTRIBUTORS for 2.2.5
  updated CHANGELOG for 2.2.5
  [Intl] Updated stubs to reflect ICU 51.2
  replaced deprecated Twig features

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php
[DependencyInjection] Test constants
merged branch gnugat/dic-test-constants (PR #8663)

This PR was squashed before being merged into the master branch (closes #8663).

Discussion
----------

[DependencyInjection] Test constants

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | **yes**
| License       | MIT

Added a test for constant support in XML configuration files.
Related PR: #8661

Commits
-------

9acedb7 [DependencyInjection] Test constants
Fix empty process argument escaping on Windows
merged branch helmer/processutils_patch (PR #8691)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #8691).

Discussion
----------

[Process] Fix empty process argument escaping on Windows

PR #6796 introduced a regression on Windows platform (symfony 2.3.0+), forgetting to escape explicitly requested empty arguments to ```""``` and return an empty string instead.

This behaviour is imo unintended and renders the component unusable for corner-cases, where you indeed want to specify an empty argument. One good example of this is assetic and compass, which (up to this day) relies on existence of empty parameters on windows.

Some panic and related links on the topic:
https://github.com/kriswallsmith/assetic/issues/455
https://github.com/kriswallsmith/assetic/pull/471
http://stackoverflow.com/questions/17001517/symfony2-3-with-compass ([diff](http://marker.to/KrctHM))
http://stackoverflow.com/questions/17135219/symfony-2-compass-with-assetic-on-windows-xp

Please consider a merge to master and a backport to 2.3.x

Commits
-------

a91537a Fix empty process argument escaping on Windows