Fix VarDecls for tuples. Closes #99. I've implemented it this way since it doesn't require any changes in the frontend. However, I think having TypeTuple expressed as LLVM struct types would make much more sense and open the door to tuple lvalues.

module nested12;

extern(C) int printf(char*, ...);

void main()
{
    func();
}

void func()
{
    void a(int i)
    {
        printf("%d\n", i);
    }

    void b()
    {
        a(42);
    }

    b();
}