Extract new base test class KernelTestClass

Ideal base class that needs access to a Kernel but not a Client such as
when testing a Command.
[Console] deprecated TableHelper in favor of Table
[Console] added the possibility to insert a table separator anywhere in a table output
[Console] make it possible to pass a style directly to Table::setStyle()
[FrameworkBundle] set a default value for gc_probability
feature #10365 [Console] deprecated TableHelper in favor of Table (fabpot)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[Console] deprecated TableHelper in favor of Table

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #9788, #9680, #9325
| License       | MIT
| Doc PR        | symfony/symfony-docs#3627

This PR makes the Table helper stateless. It also adds a way to define global styles and to change/tweak existing styles easily.

The second commit adds the possibility to add a separator anywhere in the table output.

Commits
-------

21784ce [Console] make it possible to pass a style directly to Table::setStyle()
14caaec [Console] added the possibility to insert a table separator anywhere in a table output
39c495f [Console] deprecated TableHelper in favor of Table
[HttpKernel] fixed serialization of the request data collector
[Serializer] added support for is.* methods in GetSetMethodNormalizer
feature #10314 [Serializer] added support for is.* methods in GetSetMethodNormalizer (tiraeth)

This PR was squashed before being merged into the 2.5-dev branch (closes #10314).

Discussion
----------

[Serializer] added support for is.* methods in GetSetMethodNormalizer

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10297
| License       | MIT
| Doc PR        | N/A

Using ``is`` prefix for boolean variables is considered a standard, not only in PHP but also in Java (from which Symfony2 derives lot standards).

I was not sure if this is BCB but answered "no". Was not sure if I should update ``CHANGELOG`` file and did so, but if you find it irrelevant, go ahead and merge without it. I don't know if I should create a PR for docs because it does not explicitly say that the normalizer supports only ``get.*`` methods as getters.

_Note: Objects that contain behaviour also can use other prefixes like ``can``, ``has``, ``should``, but their presence in ``GetSetMethodNormalizer`` is relevant as they do not provide state (``has`` is debatable)._

Commits
-------

480219f [Serializer] added support for is.* methods in GetSetMethodNormalizer
bug #10367 [HttpKernel] fixed serialization of the request data collector (fabpot)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[HttpKernel] fixed serialization of the request data collector

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10361
| License       | MIT
| Doc PR        | n/a

This fixes a regression introduced in #10352.

Commits
-------

6102f99 [HttpKernel] fixed serialization of the request data collector
[ClassLoader] A PSR-4 compatible class loader
feature #10100 [ClassLoader] A PSR-4 compatible class loader (derrabus)

This PR was squashed before being merged into the 2.5-dev branch (closes #10100).

Discussion
----------

[ClassLoader] A PSR-4 compatible class loader

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

This is a PSR-4 compatible class loader that I'd like to contribute to the ClassLoader component. Since PSR-4 is the most recent FIG standard for an autoloader, I thought a compatible loader should be part of a feature-complete ClassLoader component.

See: http://www.php-fig.org/psr/psr-4/

PSR-4 does neither replace PSR-0, nor are those standards 100% compatible. This is why I implemented the standard as a new class.

If you decide that my PR is worth merging, I would also provide a PR for symfony-docs with a documentation.

Commits
-------

6837df3 [ClassLoader] A PSR-4 compatible class loader
Added a translation:debug command
[FrameworkBundle] Add HHVM support for built-in web server
feature #10017 [FrameworkBundle] Add HHVM support for built-in web server (RickySu)

This PR was squashed before being merged into the 2.5-dev branch (closes #10017).

Discussion
----------

[FrameworkBundle] Add HHVM support for built-in web server

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

Using HHVM as built-in web server for development from console.

```
hhvm app/console server:run
```

Commits
-------

66798ba9 [FrameworkBundle] Add HHVM support for built-in web server
[Translation] Added template for relative file paths
Added a ConcreteDumper
Changed placeholders
[FrameworkBundle] refactored the built-in web server
[FrameworkBundle] fixed edge cases for translation:debug and tweaked the output