mark-p-thomas : Route Stats

While any polyline segment has some concept of a length, routes are actual paths in the real world. As such, these include additional stats such as slope and height. Slope is further signed in case a user only wants stats that apply to uphill or downhill travel. Implementing or referencing the IRangeStatsResult interface allows each route criteria to include a broad range of stats.

Each Route stat is a higher-level concept that includes a suite of lower-level stats, such as sum, mean, median, max/min, standard deviations, and ranges.