[2.3] Examples that points to the DataCollectorListener should be removed.
Removed outdated translations from the official list
Fix documentation for group_sequence_provider
document multiple recipients in XML configs

Adds an example on how to configure multiple recipients in Monolog
for sending log entries as e-mails.
[Reference] fix namespace in Expression constraint
tweaks for the web server configuration chapter
Fixed minor typos.
Removing extra whitespace
bug #4153 [Reference] fix namespace in Expression constraint (xabbuh)

This PR was merged into the 2.4 branch.

Discussion
----------

[Reference] fix namespace in Expression constraint

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.4+
| Fixed tickets |

Commits
-------

1deabde [Reference] fix namespace in Expression constraint
feature #4142 [Cookbook][Configuration] tweaks for the web server configuration chapter (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Cookbook][Configuration] tweaks for the web server configuration chapter

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

Tweaks to #3915 as suggested by @weaverryan.

Commits
-------

93bbd14 tweaks for the web server configuration chapter
Added the schema_filter option to the reference
feature #4150 Added the schema_filter option to the reference (peterrehm)

This PR was submitted for the 2.5 branch but it was merged into the 2.3 branch instead (closes #4150).

Discussion
----------

Added the schema_filter option to the reference

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

Shall the optional setting be added to XML as well? How?
I am unsure if it is actually to which version this relates to the DoctrineBundle.

Relates to doctrine/migrations#101

Commits
-------

20cba4e Added the schema_filter option to the reference
Merge branch '2.3' into 2.4

* 2.3:
  Added the schema_filter option to the reference
  Removing extra whitespace
  tweaks for the web server configuration chapter
Merge branch '2.4' into 2.5

* 2.4:
  Added the schema_filter option to the reference
  Removing extra whitespace
  tweaks for the web server configuration chapter
  [Reference] fix namespace in Expression constraint
Added custom format page to translation component
Link from introduction section
Small fixes
Cleanups
Fixed version for composer install
Improvements based on comments