Update v5 API

[1ec5]

This PR reacts to various changes to the v5 API made over the past few weeks:

• Updated ManeuverType values.
• A request has only one transport type, corresponding to the profile, but for every request, each step may have a different, more granular transport type. So now an MBRouteStep’s transportType has a distinct datatype. The transportType property matters particularly when the maneuverType is HeedWarning.
• Updated v5 URL parameters.
• v5 route legs currently lack route summaries, so here I’m synthesizing them using logic similar to what would be done on the server side. This code can be very expensive, so I hope to remove it as soon as possible.

/cc @karenzshea @bsudekum @freenerd

[1ec5]

97378ca follows up by inverting the logic for when to synthesize a route name.