Merge branch 'master' into jgrpp

# Conflicts:
#	src/company_cmd.cpp
#	src/core/overflowsafe_type.hpp
#	src/economy.cpp
#	src/engine_base.h
#	src/ground_vehicle.cpp
#	src/group_gui.cpp
#	src/industry_cmd.cpp
#	src/industry_gui.cpp
#	src/newgrf_commons.cpp
#	src/newgrf_engine.cpp
#	src/newgrf_industries.cpp
#	src/newgrf_object.cpp
#	src/newgrf_roadstop.cpp
#	src/newgrf_station.cpp
#	src/rail_gui.cpp
#	src/road_cmd.h
#	src/road_gui.cpp
#	src/saveload/afterload.cpp
#	src/script/api/script_log.cpp
#	src/script/api/script_log.hpp
#	src/settings_gui.cpp
#	src/settingsgen/settingsgen.cpp
#	src/station_cmd.cpp
#	src/station_cmd.h
#	src/station_gui.cpp
#	src/strgen/strgen.cpp
#	src/string_func.h
#	src/string_type.h
#	src/table/settings/network_private_settings.ini
#	src/tests/math_func.cpp
#	src/textfile_gui.cpp
#	src/timetable_gui.cpp
#	src/town_cmd.cpp
#	src/vehicle.cpp
#	src/waypoint_cmd.cpp
#	src/waypoint_cmd.h
#	src/widgets/dropdown.cpp

src/engine.cpp

@@ -673,8 +673,8 @@ void CalcEngineReliability(Engine *e, bool new_month)
 		re = Engine::Get(re->info.variant_id);
 	}
 
-	uint age = re->age;
-	if (new_month && re->index > e->index && age != MAX_DAY) age++; /* parent variant's age has not yet updated. */
+	uint32 age = re->age;
+	if (new_month && re->index > e->index && age != INT32_MAX) age++; /* parent variant's age has not yet updated. */
 
 	/* Check for early retirement */
 	if (e->company_avail != 0 && !_settings_game.vehicle.never_expire_vehicles && e->info.base_life != 0xFF) {
@@ -1187,7 +1187,7 @@ void EnginesMonthlyLoop()
 		bool refresh = false;
 		for (Engine *e : Engine::Iterate()) {
 			/* Age the vehicle */
-			if ((e->flags & ENGINE_AVAILABLE) && e->age != MAX_DAY) {
+			if ((e->flags & ENGINE_AVAILABLE) && e->age != INT32_MAX) {
 				e->age++;
 				CalcEngineReliability(e, true);
 				refresh = true;