Import cargo type orders patch

https://www.tt-forums.net/viewtopic.php?p=1047749#p1047749

Port to current trunk, resolve various conflicts, etc.
Adjust bit allocations for CmdModifyOrder.
Use save_ext framework for added order flags.

src/saveload/extended_ver_sl.cpp

@@ -45,6 +45,8 @@ std::vector<uint32> _sl_xv_discardable_chunk_ids;           ///< list of chunks
 static const uint32 _sl_xv_slxi_chunk_version = 0;          ///< current version os SLXI chunk
 
 const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
+	{ XSLFI_CARGO_TYPE_ORDERS,      XSCF_NULL,                1,   1, "cargo_type_orders",         NULL, NULL, NULL        },
+
 	{ XSLFI_NULL, XSCF_NULL, 0, 0, NULL, NULL, NULL, NULL },// This is the end marker
 };
 

src/saveload/extended_ver_sl.h

@@ -21,6 +21,7 @@
  */
 enum SlXvFeatureIndex {
 	XSLFI_NULL                          = 0,      ///< Unused value, to indicate that no extended feature test is in use
+	XSLFI_CARGO_TYPE_ORDERS,                      ///< Cargo-specific load/unload order flags
 
 	XSLFI_SIZE,                                   ///< Total count of features, including null feature
 };

src/saveload/order_sl.cpp

@@ -113,6 +113,7 @@ const SaveLoad *GetOrderDescription()
 		 SLE_CONDVAR(Order, wait_time,      SLE_UINT16,  67, SL_MAX_VERSION),
 		 SLE_CONDVAR(Order, travel_time,    SLE_UINT16,  67, SL_MAX_VERSION),
 		 SLE_CONDVAR(Order, max_speed,      SLE_UINT16, 172, SL_MAX_VERSION),
+		SLE_CONDARR_X(Order, cargo_type_flags, SLE_UINT8, NUM_CARGO, 0, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_CARGO_TYPE_ORDERS, 1)),
 
 		/* Leftover from the minor savegame version stuff
 		 * We will never use those free bytes, but we have to keep this line to allow loading of old savegames */