Elevation data

This is a big project, but with small steps. Roughly:

1) Get better elevation data, either fixing the bugs in the `srtm.rs` impl or preferably using the better LIDAR data around Seattle. I have some pointers for that in an email somewhere; remind me to post them

2) Figure out how elevation change affects the standard bicyclist speed. Incorporate that in the simulation and pathfinding cost function

3) Render the elevation layer much more understandably. Isochrones are the thing people are familiar with, probably should give that a shot

I can give pointers to relevant code when needed

The issue mentions srtm.rs for elevation data and points to LIDAR data for Seattle. Start by examining the srtm.rs implementation for bugs. Look for simulation and pathfinding modules to understand how elevation change could affect bicyclist speed. The goal is to improve elevation data, incorporate it into simulation cost functions, and render an elevation layer more clearly, possibly using isochrones.

Scritto dal modello di indicizzazione a partire dal testo della issue.