Not adding prefixes to names in the same namespace

[marekdedic]

Basically a continuation of #457.

Here, I focus on names in same namespace, such as

namespace X\Y {
    class Foo {}
}

namespace X {
    $foo = new Y\Foo();
}

Here, Y\Foo doesn't need to be prefixed or made FQ as it is referencing something in the same namespace. So let's make php-scoper not add the prefix where it isn't necessary :)

[theofidry]

Thanks a lot @marekdedic