Implement RouteStep equality

[1ec5]

RouteStep currently inherits the == operator from NSObject, so it only considers whether two RouteStep objects are the same object. RouteStep should override the == operator to indicate whether the objects represent the same logical step. It should at least consider the step’s coordinates, maneuver type, and maneuver direction. Should it consider anything else about the step?

/cc @frederoni @bsudekum

[1ec5]

RouteStep conforms to Equatable as of #382, though I think there was an equality method before that.