Added '@@' escaping strategy for YamlFileLoader and YamlDumper

Added the possibility to to use '@@' as an escaping strategy for
parameters that should be treated as strings but start with '@'
(i.e. safe mailer passwords).
merged branch tPl0ch/feature/yaml-parameter-escape (PR #7357)

This PR was submitted for the master branch but it was merged into the 2.1 branch instead (closes #7357).

Discussion
----------

[DependencyInjection] Added @@ escaping strategy for YamlFileLoader and YamlDumper

Added the possibility to to use ```@@``` as an escaping strategy for
parameters that should be treated as strings but start with ```@```
(i.e. safe mailer passwords).

This PR is deprecating https://github.com/symfony/symfony/pull/7307, since as a new feature it has to be compared against the master branch.

| Q | A |
| ------ | ------ |
|  Bug fix?  |  yes  |
|  New feature?  |  yes  |
|  BC breaks?  |  no  |
|  Deprecations?  |  no  |
|  Tests pass?  |  yes  |
|  Fixed tickets  |  #4889  |

Commits
-------

8cdf387 [DependencyInjection] Added '@@' escaping strategy for YamlFileLoader and YamlDumper
[Console] Progress helper enhancements
merged branch pkruithof/progress-helper-enhancements (PR #7300)

This PR was squashed before being merged into the master branch (closes #7300).

Discussion
----------

[Console] Progress helper enhancements

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

Two enhancements:

1. The progress bar clears the current line before writing the current progress. This can cause some flickering in the terminal. I've modified the write method to append whitespace to the line to be written, so it matches the previous line's length.
2. Added a `setCurrent` method to set the current progress. Rather than advancing by 1 or more steps, sometimes you want to just set the current state. For example if you are downloading a file, and a callback provides you with the current download status. A workaround for this could be to keep track of the previous event, calculate the difference, and advancing by the diff. But it's easier to just set the current progress.

Sidenotes:
* The [`overwrite`](https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Console/Helper/ProgressHelper.php#L387) method copied documentation of the Output's [`write`](https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Console/Output/Output.php#L139) method. The difference is, the overwrite method does not handle an array of messages. I've updated the documentation for this.
* The helper uses `strlen` to calculate line lengths. This could cause a problem when using multibyte strings. I'd change it to `mb_strlen`, but I'm not sure if the `mb_string` extension is required by Symfony.

Commits
-------

5ae76f0 [Console] Progress helper enhancements
[Console] added a note in the CHANGELOG for the previous merge, fixed some CS
updated various CHANGELOG files that were not updated when the PRs were merged
merged branch jfsimon/finder-access-denied-exception (PR #7256)

This PR was merged into the master branch.

Discussion
----------

[Finder] Adds AccessDeniedException

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #6981

Commits
-------

714ace8 [finder] Introduced AccessDeniedException
[Finder] added a CHANGELOG entry for the previous merge
#7106 - fix for ZTS builds
merged branch lizjulien/7106 (PR #7248)

This PR was submitted for the master branch but it was merged into the 2.1 branch instead (closes #7248).

Discussion
----------

#7106 - check php version for getcwd()

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7106
| License       | MIT

Commits
-------

11d3855  #7106 - fix for ZTS builds
merged branch DHorchler/2.1 (PR #7193)

This PR was merged into the 2.1 branch.

Discussion
----------

Routing issue with installation in a sub-directory

ref: https://github.com/symfony/symfony/issues/7129

Commits
-------

8d9cd42 Routing issue with installation in a sub-directory ref: https://github.com/symfony/symfony/issues/7129
Merge branch '2.1' into 2.2

* 2.1:
  #7106 - fix for ZTS builds
  Added '@@' escaping strategy for YamlFileLoader and YamlDumper
  [Yaml] fixed bugs with folded scalar parsing
  [Form] made DefaultCsrfProvider using session_status() when available
  Added unit tests to Dumper
  Update .travis.yml (closes #7355)
  [HttpFoudantion] fixed Request::getPreferredLanguage()
  Revert "merged branch jfsimon/issue-6928 (PR #7378)"
  Routing issue with installation in a sub-directory ref: https://github.com/symfony/symfony/issues/7129

Conflicts:
	.travis.yml
	src/Symfony/Bundle/FrameworkBundle/Routing/Router.php
	src/Symfony/Component/Routing/RouteCollection.php
merged branch Smart-Core/master (PR #7076)

This PR was merged into the master branch.

Discussion
----------

[2.3] Add missing WinCacheClassLoader

Commits
-------

af86e5b Add missing WinCacheClassLoader
[ClassLoader] added missing CHANGELOG entry for previous merge
Merge branch '2.2'

* 2.2:
  #7106 - fix for ZTS builds
  Added '@@' escaping strategy for YamlFileLoader and YamlDumper
  [Yaml] fixed bugs with folded scalar parsing
  [Form] made DefaultCsrfProvider using session_status() when available
  Added unit tests to Dumper
  Update .travis.yml (closes #7355)
  [HttpFoudantion] fixed Request::getPreferredLanguage()
  Revert "merged branch jfsimon/issue-6928 (PR #7378)"
  Routing issue with installation in a sub-directory ref: https://github.com/symfony/symfony/issues/7129
[2.3] [Routing] Added access to querystring in RequestContext
merged branch lmcnearney/querystring (PR #7028)

This PR was squashed before being merged into the master branch (closes #7028).

Discussion
----------

[2.3] [Routing] Added access to querystring in RequestContext

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

This is related to a Silex change request: https://github.com/fabpot/Silex/pull/623

Commits
-------

4a2b755 [2.3] [Routing] Added access to querystring in RequestContext
merged branch marcosQuesada/serializer/denormalize-camelcase (PR #6951)

This PR was merged into the master branch.

Discussion
----------

[2.3] [Serializer] Enabled camelCase format to be used on denormalize method

 Enabled camelCase formater , that way when hydrating from arrays, attributes as attribute_name could be implemented as attributteName parameter, with getAttributeName and setAttributeName, giving different formating option from setAttribute_name  getAttribute_name.

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

Commits
-------

fbffdf0 Enabled camelCase format to be used on denormalize method, that way camel_case attribute can be used on object as getCamelCase()
added missing entries in CHANGELOGs
moved the request scope creation to the ContainerAwareHttpKernel class