Generates the right method name for actor classes.

It seems there is a unexpected behavior in the `\ReflectionMethod` contructor when used with classes with an aliased method.  E.g. the Asserts module use a trait and aliases the assertion methods, when we use:
```php
$method = new \ReflectionMethod('\Codeception\Module\Asserts', 'seeTrue');
echo $method->name;
```
it shows `assertTrue`, the method name in the trait, but when we use:
```php
$class = new \ReflectionClass('\Codeception\Module\Asserts');
$method = $class->getMethod('seeTrue');
echo $method->name;
```
it shows `seeTrue`, the aliased name in the class, which seems like the desirable behavior.