This PR was merged into the 3.2-dev branch.

Discussion
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[Debug] Better error handling

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | -
| Fixed tickets | -
| License       | MIT
| Doc PR        | symfony/symfony-docs#6870

1. Send the raw exception in the log context instead of custom formatting
2. Add config option to log/throw in Symfony all PHP errors
3. Always use an exception when a PHP error occurs
4. Expand exception in the log context in the web developer toolbar
5. Use the dumper to dump log context in the web developer toolbar

---

I used the following code to produce screenshots:

```php
public function indexAction(Request $request)
    {
        $this->get('logger')->info('A log message with an exception', ['exception' => new \Exception('this exception will be logged')]);

        error_reporting(0);
        for ($i=0; $i < 15; $i++) {
            if ($i == 5) {
                error_reporting(E_ALL);
            }
            if ($i == 10) {
                error_reporting(0);
            }

            trigger_error("Trigger error avec E_USER_NOTICE", E_USER_NOTICE);
        }

        error_reporting(E_ALL);

        @trigger_error("trigger_error avec E_USER_DEPRECATED", E_USER_DEPRECATED);
        trigger_error("trigger_error avec E_USER_DEPRECATED (not silent)", E_USER_DEPRECATED);
// ...
```

![screenshot16](https://cloud.githubusercontent.com/assets/408368/17582279/2c4239b0-5fab-11e6-8428-2eaa7372cce3.png)

![screenshot17](https://cloud.githubusercontent.com/assets/408368/17582287/30cad1ea-5fab-11e6-9b0b-de0fa9f3913b.png)

![screenshot18](https://cloud.githubusercontent.com/assets/408368/17582291/348bb574-5fab-11e6-83b0-5bfaac080838.png)

Commits
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8f24549 [Debug] Better error handling

…ions (lyrixx)

This PR was merged into the master branch.

Discussion
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[Debug] Added configuration reference for new debug options

Commits
-------

7ea70c8 [Debug] Added configuration reference for new debug options