Merge branch 'master' into jgrpp

Remove the viewport sign cache as this is now superseded by the kd tree
implementation

# Conflicts:
#	src/crashlog.cpp
#	src/lang/english.txt
#	src/misc.cpp
#	src/pathfinder/follow_track.hpp
#	src/pbs.cpp
#	src/rail_cmd.cpp
#	src/saveload/vehicle_sl.cpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/ship_cmd.cpp
#	src/station.cpp
#	src/station_base.h
#	src/station_cmd.cpp
#	src/table/settings.ini
#	src/thread/thread_morphos.cpp
#	src/town_cmd.cpp
#	src/train_cmd.cpp
#	src/viewport.cpp
#	src/waypoint.cpp

src/order_cmd.cpp

@@ -2248,7 +2248,6 @@ void CheckOrders(const Vehicle *v)
 				} else if (v->type == VEH_AIRCRAFT &&
 							(AircraftVehInfo(v->engine_type)->subtype & AIR_FAST) &&
 							(st->airport.GetFTA()->flags & AirportFTAClass::SHORT_STRIP) &&
-							_settings_game.vehicle.plane_crashes != 0 &&
 							!_cheats.no_jetcrash.value &&
 							message == INVALID_STRING_ID) {
 					message = STR_NEWS_PLANE_USES_TOO_SHORT_RUNWAY;