adds support for PTY mode
adds convenience method mustRun
attempts to fix tests on Travis
adds cache for isPtySupported()
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.
Add type detection. Needed by pdo_dblib
bug #9747 [DoctrineBridge] Fix: Add type detection. Needed by pdo_dblib (iamluc)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #9747).

Discussion
----------

[DoctrineBridge] Fix: Add type detection. Needed by pdo_dblib

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

Commits
-------

75f5cc3 Add type detection. Needed by pdo_dblib
[CssSelector] fixed numeric attribute issue
bug #9970 [CssSelector] fixed numeric attribute issue (jfsimon)

This PR was merged into the 2.3 branch.

Discussion
----------

[CssSelector] fixed numeric attribute issue

This PR adds a cast from number to string when parsing a numeric attribute value.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9968

Commits
-------

613535a [CssSelector] fixed numeric attribute issue
[TwigBridge] Update min. version of Twig

The minimal version of Twig must be 1.12 because of usage the method `Twig_SimpleFunction` that was added in that version.
bug #9983 [TwigBridge] Update min. version of Twig (stloyd)

This PR was merged into the 2.3 branch.

Discussion
----------

[TwigBridge] Update min. version of Twig

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

The minimal version of Twig must be 1.12 because of usage the method `Twig_SimpleFunction` that was added in that version.

Commits
-------

c003291 [TwigBridge] Update min. version of Twig
Prevent WDT from creating a session
Fix for null values in assosiated properties when using UniqueEntityValidator
bug #9979 [Doctrine Bridge][Validator] Fix for null values in assosiated properties when using UniqueEntityValidator (vpetrovych)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #9979).

Discussion
----------

[Doctrine Bridge][Validator] Fix for null values in assosiated properties when using UniqueEntityValidator

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7382
| License       | MIT
| Doc PR        |

This fixes issue with UniqueEntityValidator when ignoreNull = false and associated property contains null value:
```
Warning: ReflectionProperty::getValue() expects parameter 1 to be object, null given in [...]/symfony2/vendor/doctrine/orm/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php line 670
```

Here's what docs say about ignoreNull:

> If this option is set to true, then the constraint will allow multiple entities to have a null value for a field without failing validation. If set to false, only one null value is allowed - if a second entity also has a null value, validation would fail.

Commits
-------

bf368bc [Doctrine Bridge][Validator] Fix for null values in assosiated properties when using UniqueEntityValidator
Fix for a couple of undefined classes in docblocks
minor #9991 Fix for a couple of undefined classes in docblocks (dave1010)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #9991).

Discussion
----------

Fix for a couple of undefined classes in docblocks

These are the 2 that I've come across, but there may be some more.

Commits
-------

3918d6d Fix for a couple of undefined classes in docblocks
[Form] Changed Form::getErrors() to return an iterator and added two optional parameters $deep and $flatten
[Form] Changed the default value of $flatten in Form::getErrors() to true
Fixed the Travis setup for HHVM
minor #9999 Fixed the Travis setup for HHVM (stof)

This PR was squashed before being merged into the 2.3 branch (closes #9999).

Discussion
----------

Fixed the Travis setup for HHVM

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

this replaces #9997 with a proper fix: fixing the cause of the issue instead of adding workarounds for it

"php -r" does not seem to behave properly in HHVM, so the check to detect HHVM has been switch to a check on the environment variable set by Travis.

Commits
-------

67d4959 Fixed the Travis setup for HHVM