Generated proxies don't respect magic methods' inherited signatures

[Ocramius]

ProxyManager will raise multiple notices due to class signature incompatibility when proxying a class like following one:

class ClassWithTypedMagicMethods
{
    public function __get(string $name) : string { return 'foo'; }
    public function __set(string $name, string $value) : string { return 'foo'; }
    public function __unset(string $name) : bool { return true; }
    public function __isset(string $name) : bool { return true; }
}

A class generation/evaluation test is sufficient for this scenario. The issue is simple: class signature should be copied, when available, instead of being constructed from scratch.

[Ocramius]

Possibly to be checked against #345

[Ocramius]

Moved to 2.1.1 - this is not a critical issue, although it will need fixing in future.