This adds the quick select algorithm that finds
the kth smallest element for any collection.
Whilst doing so it also partially sorts the collection.
I have also included the option to use different pivoting functions
including median of medians which makes the quick select have
a truely linear time complexity at the costs of enormous overhead,
so this that only really useful for really large datasets.
The same was chosen to reflect the fact that it modifies
the collection in place during the selection process.
