Enhance directions view and capabilities

[jkwening]

Enhance directions view

• Customize routing text pane: partial map and text view, full text view, and hidden
• Include alternate routes in preview
  • Allow clicking on route lines to select alternative routes
• Add reverse directions feature (http://www.liedman.net/leaflet-routing-machine/tutorials/interaction/)
• Go (Start) directions feature: next/previous button (Implement start/end navigation feature for directions #297)
• Add feature to save directions and get saved directions from backend (Save directions feature #296)

[khusbuchandra]

@jkwening , I can help out if you need. Or are the pieces already covered?

[khusbuchandra]

@jkwening , for alternative routes, do we intend to use other apis like Graphhopper or any other server?
http://www.liedman.net/leaflet-routing-machine/tutorials/alternative-routers/

[jkwening]

@khusbuchandra regarding alternative directions, I'm referring to the instance when there are more than one route returned for directions result. Currently, the directions text pane shows multiple routes when available but the map doesn't display the alternate routes. We should display them. I believe it just simple leaflet-routing feature that needs to be toggled on.