[VarDumper] fix control chars styling
[EventDispatcher] perf optim
[HttpKernel] fix DebugHandlersListener
updated CHANGELOG for 2.3.21
update CONTRIBUTORS for 2.3.21
updated VERSION for 2.3.21
bumped Symfony version to 2.3.22
updated CHANGELOG for 2.5.6
updated VERSION for 2.5.6
bumped Symfony version to 2.5.7
Improved the phpdoc for security token classes
[Security][listener] change priority of switchuser
minor #12310 Improved the phpdoc for security token classes (stof)

This PR was merged into the 2.3 branch.

Discussion
----------

Improved the phpdoc for security token classes

| 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

This will avoid to have Scrutinizer complaining that we pass an array of string rather than an array of RoleInterface for instance.

Commits
-------

7b6d115 Improved the phpdoc for security token classes
bug #12313 [Security][listener] change priority of switchuser (aitboudad)

This PR was merged into the 2.3 branch.

Discussion
----------

[Security][listener] change priority of switchuser

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

Hi,
I have the following users:
  - Manager: Allowed to access to (/admin) and has a role ROLE_ALLOWED_TO_SWITCH
  - Partner: Allowed to access to (/partner)

When I attempt to switch to partner user I get "Access denied", well I think the switchuser listener must be registred before access listener.

Commits
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5f8047d [Security][listener] change priority of switchuser
don't translate error messages twice

As @stof pointed out in #12164, error messages are already translated
when they are passed to the template.
Break infinite loop while resolving aliases
bug #12316 Break infinite loop while resolving aliases (chx)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #12316).

Discussion
----------

Break infinite loop while resolving aliases

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

Commits
-------

acbde50 Break infinite loop while resolving aliases
bug #12322 don't translate error messages twice (xabbuh)

This PR was merged into the 2.6-dev branch.

Discussion
----------

don't translate error messages twice

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

As @stof pointed out in #12164, error messages are already translated
when they are passed to the template.

Commits
-------

4bd8661 don't translate error messages twice
Remove aligned '=>' and '='
minor #12293 Remove aligned '=>' and '=' (disquedur)

This PR was squashed before being merged into the 2.3 branch (closes #12293).

Discussion
----------

Remove aligned '=>' and '='

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | [https://github.com/symfony/symfony/issues/12284]
| License       | MIT

Could you said to me if i should make an other PR for 2.5 branch.

Commits
-------

51312d3 Remove aligned '=>' and '='