message: Simplify and fix bug (abs() takes and returns integral types)
diff: @@ -289,7 +289,7 @@ int discrSeg(const Point2D &a,
  int idx)
  {
  // Deal with degenerate segments
  - if (abs(a[0] - b[0]) < PTINY) { return 0; }
  + if (b[0] - a[0] < PTINY) { return 0; }
  if (a[1] < PTINY && b[1] < PTINY) { return 0; }
  int total_count = count_segment_prisms(levels);
  