Ignore null value in comparison validators
replaced deprecated Twig features
[Intl] Updated stubs to reflect ICU 51.2
updated CHANGELOG for 2.2.5
update CONTRIBUTORS for 2.2.5
updated VERSION for 2.2.5
bumped Symfony version to 2.2.6
bumped Symfony version to 2.3.4-DEV
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 fabpot/twig-deprecated-features (PR #8675)

This PR was merged into the 2.2 branch.

Discussion
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replaced deprecated Twig features

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

As Symfony depends on Twig 1.11+, removing the usage of deprecated features will allow Symfony 2.2+ to work with Twig 2.0.

Commits
-------

322f880 replaced deprecated Twig features
made the filesystem loader compatible with Twig 2.0

Without adding the exists() method, the code happens to work by chance,
just because the current implementation of Twig exits() method calls
findTemplate().

But we know that it won't be the case anymore as of Twig 2.0.
merged branch fabpot/twig-filesystem-exists (PR #8677)

This PR was submitted for the master branch but it was merged into the 2.2 branch instead (closes #8677).

Discussion
----------

[TwigBundle] made the filesystem loader compatible with Twig 2.0

| Q             | A
| ------------- | ---
| Bug fix?      | yes (for Twig 2.x)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Without adding the exists() method, the code happens to work by chance,
just because the current implementation of Twig exits() method calls
findTemplate().

But we know that it won't be the case anymore as of Twig 2.0.

Commits
-------

d00548b [TwigBundle] made the filesystem loader compatible with Twig 2.0
Fixed bug introduced in #8675
merged branch WouterJ/fix_bug (PR #8696)

This PR was merged into the 2.2 branch.

Discussion
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[2.2][TwigBridge] Fix form_enctype bug

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

After a copy/past error in #8675, `{{ form_enctype() }}` was not working because it results in a `Class "Symfony\Bridge\Twig\Node\FormEnctypeNode" not found` error.

This should only be merged in 2.2, as of 2.3 this is moved to the `Symfony\Bridge\Twig\Node\FormEnctypeNode` class

Commits
-------

e0c7d3d Fixed bug introduced in #8675
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
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
merged branch EmmanuelVella/validators (PR #8577)

This PR was merged into the 2.3 branch.

Discussion
----------

Validators

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

This PR avoid comparison validators to be executed if the compared value is null.

Commits
-------

48338fc Ignore null value in comparison validators
Make sure ContextErrorException is loaded during compile time errors