Add support for loading trunk savegames versions 293 - 299 (12.0)

Use modified upstream saveload implementation for these versions
Re-arrange headers to support multiple saveload implementations

src/cargopacket.h

@@ -18,7 +18,7 @@
 #include "vehicle_type.h"
 #include "company_type.h"
 #include "core/multimap.hpp"
-#include "saveload/saveload.h"
+#include "saveload/saveload_common.h"
 #include <deque>
 
 /** Unique identifier for a single cargo packet. */
@@ -36,6 +36,12 @@ template <class Tinst, class Tcont> class CargoList;
 class StationCargoList; // forward-declare, so we can use it in VehicleCargoList.
 extern SaveLoadTable GetCargoPacketDesc();
 
+namespace upstream_sl {
+	extern upstream_sl::SaveLoadTable GetCargoPacketDesc();
+	class SlVehicleCommon;
+	class SlStationGoods;
+}
+
 typedef uint32 TileOrStationID;
 
 void ClearCargoPacketDeferredPayments();
@@ -70,6 +76,7 @@ private:
 	friend class StationCargoList;
 	/** We want this to be saved, right? */
 	friend SaveLoadTable GetCargoPacketDesc();
+	friend upstream_sl::SaveLoadTable upstream_sl::GetCargoPacketDesc();
 	friend void Load_CPDP();
 public:
 	/** Maximum number of items in a single cargo packet. */
@@ -340,6 +347,7 @@ protected:
 public:
 	/** The station cargo list needs to control the unloading. */
 	friend class StationCargoList;
+	friend upstream_sl::SlVehicleCommon;
 	/** The super class ought to know what it's doing. */
 	friend class CargoList<VehicleCargoList, CargoPacketList>;
 	/** The vehicles have a cargo list (and we want that saved). */
@@ -495,6 +503,7 @@ public:
 	friend class CargoList<StationCargoList, StationCargoPacketMap>;
 	/** The stations, via GoodsEntry, have a CargoList. */
 	friend SaveLoadTable GetGoodsDesc();
+	friend upstream_sl::SlStationGoods;
 
 	friend class CargoLoad;
 	friend class CargoTransfer;