GetSigniature fails on nested generic types

[ZacharyPatten]

Description

This is the same as #29 but for the GetSigniature extension method.

class A
{
    class B<D>
    {
        class C<E> {  }
    }
}

typeof(A.B<int>.C<string>).GetSigniature();
typeof(A.B<>.C<>).GetSigniature();

It either throws an InvalidOperationException or returns too many generics for the nested generic signiature.