Overlaying a route

[psychemedia]

I was wondering how easy it would be to overlay an actual route, presented as a geojson file, perhaps, or specified as a set of waypoints to a routefinding service (that would presumably return a geojson route) on a map, perhaps as a thick dotted line?

[ColCarroll]

There was some conversation in #7 that seems related: right now, we forget about the coordinates as soon as the data is read in, and do some ad-hoc mapping of rows/columns of a matrix to (x, y) coordinates in matplotlib.

Having a layer that maps between (lat, long), (x, y), and (row, column) seems like it would help with a lot of this, though I probably won't have time to take that up.