Black box: older recordings read as before, single vehicles told apart, each platform end its own tolerance

- A light pattern asked for in a recording made before the lamps were
  written is checked as the signal it shows, as before.
- Whether the couplings were written is told by the format (the
  movement in the cab samples), not by there being any: a recording
  where every train is a single vehicle has none, and the user going
  over to another vehicle left the timetable shown.
- The 2 m a train may stand off the platform is at each end, not for
  both together.

Eu07.BlackBox/HeadCodes.cs

@@ -101,7 +101,8 @@ public static class HeadCodes
         var pattern = (Lights)hint;
         if (usual == HeadCode.Pc1 && pattern == (Lights.RedMarkerLeft | Lights.HeadlightRight | Lights.HeadlightUpper))
             return Shows(HeadCode.Pc2, lit, equipped);
-        return (lit & ~HighBeams) == (equipped is { } lamps ? pattern & lamps : pattern);
+        // a recording made before the lamps were written: the signal the pattern shows, as before
+        return equipped is { } lamps ? (lit & ~HighBeams) == (pattern & lamps) : Of(lit) == Of(pattern);
     }
 
     /// <summary>