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/extended_ver_sl.h

@@ -47,6 +47,7 @@ enum SlXvFeatureIndex {
 	XSLFI_CARGO_TYPE_ORDERS,                      ///< Cargo-specific load/unload order flags
 	XSLFI_EXTENDED_GAMELOG,                       ///< Extended gamelog
 	XSLFI_STATION_CATCHMENT_INC,                  ///< Station catchment radius increase
+	XSLFI_CUSTOM_BRIDGE_HEADS,                    ///< Custom bridge heads
 
 	XSLFI_RIFF_HEADER_60_BIT,                     ///< Size field in RIFF chunk header is 60 bit
 	XSLFI_HEIGHT_8_BIT,                           ///< Map tile height is 8 bit instead of 4 bit, but savegame version may be before this became true in trunk