UPGRADE FROM 2.4 to 2.5

Routing

Added a new optional parameter $requiredSchemes to Symfony\Component\Routing\Generator\UrlGenerator::doGenerate()

Form

The method FormInterface::getErrors() now returns an instance of Symfony\Component\Form\FormErrorIterator instead of an array. This object is traversable, countable and supports array access. However, you can not pass it to any of PHP's array_* functions anymore. You should use iterator_to_array() in those cases where you did.

Before:
```
$errors = array_map($callback, $form->getErrors());
```
After:
```
$errors = array_map($callback, iterator_to_array($form->getErrors()));
```
The method FormInterface::getErrors() now has two additional, optional parameters. Make sure to add these parameters to the method signatures of your implementations of that interface.

Before:
```
public function getErrors()
{
```
After:
```
public function getErrors($deep = false, $flatten = false)
{
```