Changes

We don't need to discard outliers, per se, just find a layer where outliers are singletons. One way to do this is to take the highest layer with a single hull (or two hulls or three hulls, etc.) If a layer never has a hull, then presumably it only has a single location or a line of locations (note that it is possible for a line to have more than 2 locations both because of multitons and because of perfect alignment, given our Google Maps accuracy), so we can discard it.

====Elbow on fraction of locations in hulls====