[MonologBridge] Ignore empty context/extra by default in the ConsoleFormatter
[Form] Added "label_format" option
[Validator] Made it possible to store the cause of a constraint violation
[Intl] Integrated ICU data into Intl component
updated CHANGELOG for 2.3.20
update CONTRIBUTORS for 2.3.20
updated VERSION for 2.3.20
bumped Symfony version to 2.3.21
updated CHANGELOG for 2.5.5
updated VERSION for 2.5.5
bumped Symfony version to 2.5.6
[Validator] Update validators.zh_CN.xlf, fix translation error
minor #12070 [Validator] Update validators.zh_CN.xlf, fix translation error (michaeljayt)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #12070).

Discussion
----------

[Validator] Update validators.zh_CN.xlf, fix translation error

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

Commits
-------

ab5aaab [Validator] Update validators.zh_CN.xlf, fix translation error
[EventDispatcher] fix doc bloc on EventDispatcherInterface
[HttpKernel] fix composer.json
feature #11496 [MonologBridge] Ignore empty context/extra by default in the ConsoleFormatter (Seldaek)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[MonologBridge] Ignore empty context/extra by default in the ConsoleFormatter

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

This adds support for https://github.com/Seldaek/monolog/pull/388 and turns it on by default since the console output is arguably meant for humans and not for machine readable stuff it makes sense I believe. /cc @Tobion

**Note:** This depends on an unreleased version of monolog and should not be merged until 1.11 is out.

Commits
-------

9b69f56 [MonologBridge] Ignore empty context/extra by default in the ConsoleFormatter
minor #12078 [HttpKernel] fix composer.json (nicolas-grekas)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[HttpKernel] fix composer.json

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

This fixes the composer.json of HttpKernel

Commits
-------

7bb768d [HttpKernel] fix composer.json
minor #12080 [EventDispatcher] fix doc bloc on EventDispatcherInterface (nicolas-grekas)

This PR was merged into the 2.3 branch.

Discussion
----------

[EventDispatcher] fix doc bloc on EventDispatcherInterface

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

The doc block says that an array of event names is accepted as input, but no implementation is compliant with that description.

Commits
-------

e3dacbd [EventDispatcher] fix doc bloc on EventDispatcherInterface
feature #12052 [Validator] Made it possible to store the cause of a constraint violation (webmozart)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[Validator] Made it possible to store the cause of a constraint violation

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

This change makes it possible to store the cause of a violation (e.g. an exception). This way it is possible to follow the trace of violations caused by exceptions up to their root.

```php
try {
    // ...
} catch (Exception $e) {
    $this->context->buildViolation('Error!')
        ->setCause($e)
        ->addViolation();
}
```

This is one step to solve #5607. See #12054.

Commits
-------

499eeb4 [Validator] Made it possible to store the cause of a constraint violation
[Form] The trace of form errors is now displayed in the profiler