[2.3] Remove possible call_user_func()
[2.5] Remove possible call_user_func()
updated CHANGELOG for 2.3.23
update CONTRIBUTORS for 2.3.23
updated VERSION for 2.3.23
bumped Symfony version to 2.3.24
updated CHANGELOG for 2.5.8
update CONTRIBUTORS for 2.5.8
updated VERSION for 2.5.8
bumped Symfony version to 2.5.9
CS fixes
Removed unused imports
minor #12837 [2.3] CS Fixes And Removed Unused Imports (GrahamCampbell)

This PR was merged into the 2.3 branch.

Discussion
----------

[2.3] CS Fixes And Removed Unused Imports

| 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 pull request fixes some cs issues in symfony 2.3.

As far as I understand, symfony's coding standards dictate that there should be no blank lines between imports and imports should not be prefixed with a slash. There are one or two other tiny fixes in here too.

Also, we should only import things that we actually *use*. :)

Commits
-------

0e4f0e7 Removed unused imports
0fc3369 CS fixes
[2.3] More cs fixes
minor #12840 [2.3] More cs fixes (GrahamCampbell)

This PR was squashed before being merged into the 2.3 branch (closes #12840).

Discussion
----------

[2.3] More cs fixes

| 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 pull request fixes some more cs issues in symfony 2.3.

I should be done with cs fixes to the 2.3 branch now. Sorry I missed these in my last pull.

Commits
-------

b034b08 [2.3] More cs fixes
Merge branch '2.3' into 2.5

* 2.3:
  [2.3] More cs fixes
  Removed unused imports
  CS fixes
  bumped Symfony version to 2.3.24
  updated VERSION for 2.3.23
  update CONTRIBUTORS for 2.3.23
  updated CHANGELOG for 2.3.23

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/EventListener/SessionListener.php
	src/Symfony/Bundle/SecurityBundle/DependencyInjection/MainConfiguration.php
	src/Symfony/Component/HttpKernel/Kernel.php
	src/Symfony/Component/HttpKernel/Tests/Bundle/BundleTest.php
	src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherDumper.php
Fixed #12845 adding a listener to an event that is currently being dispatched will not result into a fatal error in TraceableEventDispatcher [EventDispatcher]
[DependencyInjection] backport perf optim

Conflicts:
	src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services11.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services19.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
[DependencyInjection] perf optim: call dirname() at most 5x
CS fixes