Merge branch 'custom_bridgeheads' into jgrpp

# Conflicts:
#	docs/landscape_grid.html
#	src/roadveh_cmd.cpp
#	src/saveload/afterload.cpp
#	src/saveload/extended_ver_sl.cpp
#	src/saveload/extended_ver_sl.h
#	src/settings_gui.cpp
#	src/settings_type.h
#	src/tunnelbridge_cmd.cpp
#	src/tunnelbridge_map.h

src/saveload/afterload.cpp

@@ -3268,6 +3268,15 @@ bool AfterLoadGame()
 		}
 	}
 
+	if (SlXvIsFeatureMissing(XSLFI_CUSTOM_BRIDGE_HEADS)) {
+		/* ensure that previously unused custom bridge-head bits are cleared */
+		for (TileIndex t = 0; t < map_size; t++) {
+			if (IsBridgeTile(t) && GetTunnelBridgeTransportType(t) == TRANSPORT_ROAD) {
+				SB(_m[t].m2, 0, 8, 0);
+			}
+		}
+	}
+
 	/* Station acceptance is some kind of cache */
 	if (IsSavegameVersionBefore(127)) {
 		Station *st;