Merge branch 'master' into jgrpp

# Conflicts:
#	cmake/CompileFlags.cmake
#	src/aircraft_cmd.cpp
#	src/blitter/32bpp_anim.cpp
#	src/cargopacket.cpp
#	src/cheat_gui.cpp
#	src/company_cmd.cpp
#	src/company_gui.cpp
#	src/core/pool_func.hpp
#	src/date.cpp
#	src/economy.cpp
#	src/error_gui.cpp
#	src/ground_vehicle.cpp
#	src/ground_vehicle.hpp
#	src/group_gui.cpp
#	src/industry_cmd.cpp
#	src/lang/dutch.txt
#	src/lang/french.txt
#	src/lang/german.txt
#	src/linkgraph/linkgraph_gui.cpp
#	src/linkgraph/mcf.cpp
#	src/network/network_content.cpp
#	src/network/network_server.cpp
#	src/network/network_udp.cpp
#	src/newgrf_engine.cpp
#	src/newgrf_station.cpp
#	src/order_cmd.cpp
#	src/order_gui.cpp
#	src/pathfinder/follow_track.hpp
#	src/pathfinder/yapf/yapf_common.hpp
#	src/saveload/saveload.cpp
#	src/settings_gui.cpp
#	src/station_cmd.cpp
#	src/station_kdtree.h
#	src/string_func.h
#	src/table/settings.ini
#	src/tgp.cpp
#	src/timetable_cmd.cpp
#	src/timetable_gui.cpp
#	src/toolbar_gui.cpp
#	src/town_cmd.cpp
#	src/train_cmd.cpp
#	src/train_gui.cpp
#	src/tree_gui.cpp
#	src/tunnelbridge_cmd.cpp
#	src/vehicle.cpp
#	src/vehicle_gui.cpp
#	src/video/sdl2_v.cpp
#	src/video/sdl_v.cpp
#	src/video/win32_v.cpp
#	src/viewport.cpp
#	src/viewport_sprite_sorter_sse4.cpp
#	src/window.cpp

src/newgrf_railtype.cpp

@@ -140,6 +140,28 @@ SpriteID GetCustomSignalSprite(const RailtypeInfo *rti, TileIndex tile, SignalTy
 	return group->GetResult();
 }
 
+/**
+ * Translate an index to the GRF-local railtype-translation table into a RailType.
+ * @param railtype  Index into GRF-local translation table.
+ * @param grffile   Originating GRF file.
+ * @return RailType or INVALID_RAILTYPE if the railtype is unknown.
+ */
+RailType GetRailTypeTranslation(uint8 railtype, const GRFFile *grffile)
+{
+	if (grffile == nullptr || grffile->railtype_list.size() == 0) {
+		/* No railtype table present. Return railtype as-is (if valid), so it works for original railtypes. */
+		if (railtype >= RAILTYPE_END || GetRailTypeInfo(static_cast<RailType>(railtype))->label == 0) return INVALID_RAILTYPE;
+
+		return static_cast<RailType>(railtype);
+	} else {
+		/* Railtype table present, but invalid index, return invalid type. */
+		if (railtype >= grffile->railtype_list.size()) return INVALID_RAILTYPE;
+
+		/* Look up railtype including alternate labels. */
+		return GetRailTypeByLabel(grffile->railtype_list[railtype]);
+	}
+}
+
 /**
  * Perform a reverse railtype lookup to get the GRF internal ID.
  * @param railtype The global (OpenTTD) railtype.