(svn r6246) -Feature: added the many times requested "send all vehicle to depot" button

it's located in the vehicle list screen and does the same as in the shared orders window (send all vehicles in list to a depot)
	it will still not inform the player if a vehicle failed to find a depot, so don't take for granted that all of them go

vehicle.h

@@ -314,6 +314,8 @@ int CheckTrainStoppedInDepot(const Vehicle *v);
 
 bool VehicleNeedsService(const Vehicle *v);
 
+int32 SendAllVehiclesToDepot(byte type, uint32 flags, bool service, PlayerID owner);
+
 typedef struct GetNewVehiclePosResult {
 	int x,y;
 	TileIndex old_tile;