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 arrays3;

void main()
{
    int[] arr;
    {arr = new int[25];}
    {assert(arr.length == 25);}
    {arr.length = arr.length + 5;}
    {assert(arr.length == 30);}
}