Distance-based instructions

[1ec5]

Turn-by-turn navigation applications need to say things like “In {distance}, {instruction}” (as the user approaches a maneuver) and “Continue on {name} for {distance}” (immediately after the user completes a maneuver). It’s easy enough for the application to provide these strings itself, but then it may not be localized as broadly as the strings in this project, and {name} won’t reflect osrm-text-instructions smarts like #77.

/cc @freenerd @bsudekum