add documentation for the TraceableEventDispatcher class
Merge branch '2.4' into 2.5
Fixed the indentation of two code blocks
#3921 - explicit 'your_user_provider' configuration parameter
feature #3916 [Component][EventDispatcher] documentation for the TraceableEventDispatcher (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[Component][EventDispatcher] documentation for the TraceableEventDispatcher

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | 2.3, 2.4
| Fixed tickets | #3879

After this has been merged, the document has to be updated for Symfony 2.5 and higher to reflect that the ``TraceableEventDispatcher`` is now part of the EventDispatcher component.

Commits
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1160f7c add documentation for the TraceableEventDispatcher class
Merge branch '2.3' into 2.4
Merge branch '2.4' into 2.5
Merge branch '2.4'
minor #3925 Fixed the indentation of two code blocks (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
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Fixed the indentation of two code blocks

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | -

Commits
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c8dbda9 Fixed the indentation of two code blocks
Merge branch '2.3' into 2.4
Merge branch '2.4' into 2.5
Merge branch '2.4'
update the TraceableEventDispatcher to reflect its movement to the EventDispatcher component in Symfony 2.5
render directory inside a code block
fix typo
minor #3927 [Cookbook][Security] Explicit 'your_user_provider' configuration parameter (zefrog)

This PR was merged into the 2.3 branch.

Discussion
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[Cookbook][Security] Explicit 'your_user_provider' configuration parameter

Following @weaverryan #3921 first improvement, I've added a few lines to the bottom note of the article, to be more precise about the ``provider`` configuration key.

Commits
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0f0376f #3921 - explicit 'your_user_provider' configuration parameter
Reorder page from simple to advanced

As a followup on https://github.com/symfony/symfony/pull/10980 I want to propose to reorder the page as the obvious way should come first. I took me way to long to find the correct way :p

I added two headers

- The default ExceptionController
- Override error templates

in order to introduce how override works and moved the controller override to the bottom as that is more advanced.
Fixed feedback from @xabbuh
Fixed feedback from @xabbuh: Templates
Added feedback from @weaverryan with a little move around.