Currently class_alias is not supported.

I need this because I would like to use imposter for Twig, but they make use of class_alias, for example here: https://github.com/twigphp/Twig/blob/2.x/src/Environment.php#L995

I think the prefix should be applied to both the alias $origin and $alias.

# from the PHP docs:
class_alias ( string $original , string $alias [, bool $autoload = TRUE ] ) : bool