Parameterize base case size.

[make-github-pseudonymous-again]

Currently hard-coded to < 2. Would allow to combine with insertion sort for base case with a single additional function call:

const quickSort = dualtco( yaroslavskiy , k );

const unstableSort = (compare, a, i, j) => {
    shuffle(a, i, j);
    quickSort(compare, a, i, j); // O(N log(N/k))
    insertionSort(compare, a, i, j); // O(kN)
};