Disallow abstract definitions from doctrine event listener registration
[Form][Validator] All index items after children are to be considered grand-children when resolving ViolationPath (fixes #11458)
[Console] Skip commands from ConsoleCommandEvent

Use case: We have different variations of the same application, for which
only certain commands are allowed. Right now this is done in a custom
Application class, but it would be much easier to just be able to skip
commands from a listener, where you can disable commands via the Event
object.

This patch provides this feature and corresponding test cases.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes - for Console tests
| Fixed tickets | None
| License       | MIT
| Doc PR        | None
Changed order of validation
[Translation] made XliffFileDumper support CDATA sections.
Made optimization deprecating modulus operator
[FrameworkBundle] Add Event Dispatcher debug command
[YAML] resolve variables in inlined YAML
[Validator] deprecate member metadata accessors in favor of existing property metadata accessors

add changelog for deprecations

fix test
add test for #11604

Adds a test case for #11604 to avoid regressions. The actual issue
has been fixed in Symfony 2.3 with the merge of #11615.
[Form] FormBuilder::getIterator() now deals with resolved children
[Validator] add getConstraints to MetadataInterface
[Validator] fixed: Expressions always valid for null values

The ExpressionValidator was incorrectly skipping validation of null or
empty string values.
Fix potential DoS when parsing HOST
Test examples from Drupal SA-CORE-2014-003
fix parsing of Authorization header
added useful reminder about form.vars.errors into UPGRADE-2.5 notes
minor #11619 added useful reminder about form.vars.errors into UPGRADE-2.5 notes (Oleg Andreyev)

This PR was submitted for the master branch but it was merged into the 2.5 branch instead (closes #11619).

Discussion
----------

added useful reminder about form.vars.errors into UPGRADE-2.5 notes

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

PR is just about upgrading UPGRADE-2.5 notes.
We've been upgrading from 2.4 to 2.5.3 and missing this part (upgrading templates)

Commits
-------

aefb1ca added useful reminder about form.vars.errors into UPGRADE-2.5 notes
Remove hard dependency of RequestContext in AssetsExtension
[Validator] Fixed wrong translation keys/messages for Collection constraint. The error messages for a missing field and an unexpected field did not match the Contraint class