Added capability to generate the list of edges in a route.
Issue #18.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>
Added capability to plot multiple routes.
Significantly sped up function to get route edges by pre-caching a dictionary of edges.
Issues #18 and #19.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>