Cache Hit/Miss Events

cc @erikformella @countrodrigo 

Turn the Geofence object into an EventEmitter and emit events on "inside", "outside" and "intersection" to see what percentage of the time is spent falling back to `point-in-polygon` versus short-circuiting via the fast lookup cache.

This will let us hand-tune the granularity for fewer cache misses on particularly onerous geofence geometries where a cache miss is 2-3 orders of magnitude more expensive.