message: add get line shifted laterally
diff: @@ -287,6 +287,17 @@ inline Line get_line_from_s_interval(Line line, float begin, float end) {
  return new_line;
  }
  +inline Line get_line_shifted_laterally(const Line& line, float lateral_shift) {
  + Line new_line;
  + for(s : line.s_.begin()) {
  + const Point2d normal = get_normal_at_s(line, s);
  + const Point2d point_at_s = get_point_at_s(line, s);
  + const Point2d shifted = point_at_s + (normal * lateral_shift);
  + new_line.add_point(shifted);
  + }
  + return new_line;
  +}
  +
  inline std::tuple<Point2d, double, uint> get_nearest_point_and_s(Line l, const Point2d &p) { // get_nearest_point
  // edge cases: empty or one-point line
  