Merge branch 'master' into jgrpp

# Conflicts:
#	src/build_vehicle_gui.cpp
#	src/engine.cpp
#	src/engine_func.h
#	src/group_gui.cpp
#	src/lang/english.txt
#	src/newgrf.cpp
#	src/saveload/oldloader_sl.cpp
#	src/timetable_cmd.cpp
#	src/timetable_cmd.h
#	src/timetable_gui.cpp

src/road.h

@@ -77,6 +77,7 @@ enum RoadTypeSpriteGroup {
 	ROTSG_DEPOT,          ///< Optional: Depot images
 	ROTSG_reserved3,      ///<           Placeholder, if we add road fences (for highways).
 	ROTSG_ROADSTOP,       ///< Required: Drive-in stop surface
+	ROTSG_ONEWAY,         ///< Optional: One-way indicator images
 	ROTSG_END,
 };