Dynamic chain for ranges?

[Ola Fosheim Grøstad]

Is there a dynamic chain primitive, so that you can add to the 
chain at runtime?

Context: the following example on the front page is interesting.

```d
void main()
{
     int[] arr1 = [4, 9, 7];
     int[] arr2 = [5, 2, 1, 10];
     int[] arr3 = [6, 8, 3];
     sort(chain(arr1, arr2, arr3));
     writefln("%s\n%s\n%s\n", arr1, arr2, arr3);
}
```

But it would be much more useful in practice if "chain" was a 
dynamic array.