Merge branch 'signal_tunnels_bridges-sx' into jgrpp

# Conflicts:
#	src/saveload/afterload.cpp
#	src/saveload/extended_ver_sl.cpp
#	src/signal.cpp
#	src/train_cmd.cpp

src/pathfinder/yapf/yapf_costrail.hpp

@@ -360,6 +360,10 @@ public:
 				}
 			}
 		}
+		if (IsTileType(tile, MP_TUNNELBRIDGE) && IsTunnelBridgeExit(tile) && DiagDirToDiagTrackdir(GetTunnelBridgeDirection(tile)) == trackdir) {
+			/* Entering a signalled bridge/tunnel from the wrong side, equivalent to encountering a one-way signal from the wrong side */
+			n.m_segment->m_end_segment_reason |= ESRB_DEAD_END;
+		}
 		return cost;
 	}