Defines solution to the Convex Hull problem proposed by Andrew, which is
a ConvexHullScan.
Andrew's ConvexHullScan devises a novel approach towards computing the partial
upper hull for a set of points by first sorting all points by their x coordinate
(breaking ties by considering the y coordinate). The partial upper hull starts with
the leftmost two points in P. ConvexHullScan extends the partial upper hull by
finding the point in P whose x coordinate comes next in sorted order after the
partial upper hull's last point Li. Once computed, the lower partial hull is
similar computed (this time by processing points from right to left). The two
partial hulls are merged to produce the final hull.