(svn r13687) [0.6] -Backport from trunk:

- Fix: Signals were not updated correctly when a player removed a non-existing track piece (r13626)
- Fix: Signal states could be propagated through waypoints built in orthogonal axis (r13589)
- Fix: Track was not removed on company bankrupcy when there was a ship on lower halftile (r13488)
- Fix: Let ships also navigate on half-tile sloped watery rail tiles (r13485)

src/signal.cpp

@@ -298,6 +298,7 @@ static SigFlags ExploreSegment(Owner owner)
 				}
 
 				if (GetRailTileType(tile) == RAIL_TILE_WAYPOINT) {
+					if (GetWaypointAxis(tile) != DiagDirToAxis(enterdir)) continue;
 					if (!(flags & SF_TRAIN) && VehicleFromPos(tile, NULL, &TrainOnTileEnum)) flags |= SF_TRAIN;
 					tile += TileOffsByDiagDir(exitdir);
 					/* enterdir and exitdir stay the same */