Support destinations

[freenerd]

Fixes #22

Also adds way_name to off ramp and on ramp. I assume that in most cases these ramps will either have no name or destinations instead.

/cc @bsudekum @1ec5 @MoKob

[MoKob]

With 5.4, we should see mostly destinations on ramps. names can happen, though, since the ramp is often named the same way as the motorway.

Should we possibly prefer destinations over names for ramps?

[freenerd]

@MoKob that is exactly what is happening, ignoring name if destinations is present.

Compare these two:

https://github.com/Project-OSRM/osrm-text-instructions/blob/69e2da43ad22fe5efbea201d7886dd9cd1cb455d/test/fixtures/v5/on_ramp/slight_right_destinations.json
https://github.com/Project-OSRM/osrm-text-instructions/blob/69e2da43ad22fe5efbea201d7886dd9cd1cb455d/test/fixtures/v5/on_ramp/slight_right.json

[freenerd]

I'm merging this quickly so it can go out on osrm-frontend Project-OSRM/osrm-frontend#187.

Still, please feel free to comment, we can fix in new PRs