Merge branch 'custom_bridgeheads' into jgrpp

# Conflicts:
#	docs/landscape.html
#	src/bridge_map.h
#	src/pbs.cpp
#	src/saveload/company_sl.cpp
#	src/saveload/extended_ver_sl.cpp
#	src/settings_type.h
#	src/signal.cpp
#	src/train_cmd.cpp
#	src/tunnel_map.h
#	src/tunnelbridge_cmd.cpp
#	src/tunnelbridge_map.h
#	src/vehicle.cpp
#	src/viewport.cpp

src/tunnel_map.h

@@ -55,6 +55,40 @@ static inline TunnelID GetTunnelIndex(TileIndex t)
 	return map_id == TUNNEL_ID_MAP_LOOKUP ? GetTunnelIndexByLookup(t) : map_id;
 }
 
+/**
+ * Checks if this tile is a rail tunnel
+ * @param t the tile that might be a rail tunnel
+ * @return true if it is a rail tunnel
+ */
+static inline bool IsRailTunnelTile(TileIndex t)
+{
+	return IsTunnelTile(t) && (TransportType)GB(_m[t].m5, 2, 2) == TRANSPORT_RAIL;
+}
+
+/**
+ * Get the reservation state of the rail tunnel
+ * @pre IsRailTunnelTile(t)
+ * @param t the tile
+ * @return reservation state
+ */
+static inline bool HasTunnelReservation(TileIndex t)
+{
+	assert(IsRailTunnelTile(t));
+	return HasBit(_m[t].m5, 4);
+}
+
+/**
+ * Set the reservation state of the rail tunnel
+ * @pre IsRailTunnelTile(t)
+ * @param t the tile
+ * @param b the reservation state
+ */
+static inline void SetTunnelReservation(TileIndex t, bool b)
+{
+	assert(IsRailTunnelTile(t));
+	SB(_m[t].m5, 4, 1, b ? 1 : 0);
+}
+
 TileIndex GetOtherTunnelEnd(TileIndex);
 
 /** Flags for miscellaneous industry tile specialities */