Added click event for loading map but no routing yet.

Still need to find out how to get a URL for the map.
Calculate distance from map route.
Compare distances and log when they do not match.

Note that this is using meters. There may be inconsitencies and it may be worth
comparing miles instead.
Add warning in trip distance area if distances differ.
Link to map of directions
Prevent distance errors showing when changing triplocation order.

This is actually due to a bug wherein changing the triplocation order does not
update the map.
Merge pull request #2 from sirbrillig/add_map_link

Add map link and warn when distance does not match map