Clear VF_CARGO_UNLOADING flag from vehicles with no cargo_payment

Bump train_through_load savegame version

src/saveload/afterload.cpp

@@ -3458,6 +3458,17 @@ bool AfterLoadGame()
 		}
 	}
 
+	if (SlXvIsFeaturePresent(XSLFI_TRAIN_THROUGH_LOAD, 0, 1)) {
+		Vehicle *v;
+		FOR_ALL_VEHICLES(v) {
+			if (v->cargo_payment == nullptr) {
+				for (Vehicle *u = v; u != NULL; u = u->Next()) {
+					if (HasBit(v->vehicle_flags, VF_CARGO_UNLOADING)) ClrBit(v->vehicle_flags, VF_CARGO_UNLOADING);
+				}
+			}
+		}
+	}
+
 	/* Road stops is 'only' updating some caches */
 	AfterLoadRoadStops();
 	AfterLoadLabelMaps();

src/saveload/extended_ver_sl.cpp

@@ -82,7 +82,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_MULTIPLE_DOCKS,         XSCF_NULL,                1,   1, "multiple_docks",            NULL, NULL, "DOCK"      },
 	{ XSLFI_TIMETABLE_EXTRA,        XSCF_NULL,                1,   1, "timetable_extra",           NULL, NULL, "ORDX"      },
 	{ XSLFI_TRAIN_FLAGS_EXTRA,      XSCF_NULL,                1,   1, "train_flags_extra",         NULL, NULL, NULL        },
-	{ XSLFI_TRAIN_THROUGH_LOAD,     XSCF_NULL,                1,   1, "train_through_load",        NULL, NULL, NULL        },
+	{ XSLFI_TRAIN_THROUGH_LOAD,     XSCF_NULL,                2,   2, "train_through_load",        NULL, NULL, NULL        },
 	{ XSLFI_ORDER_EXTRA_DATA,       XSCF_NULL,                1,   1, "order_extra_data",          NULL, NULL, NULL        },
 	{ XSLFI_WHOLE_MAP_CHUNK,        XSCF_NULL,                1,   1, "whole_map_chunk",           NULL, NULL, "WMAP"      },
 	{ XSLFI_ST_LAST_VEH_TYPE,       XSCF_NULL,                1,   1, "station_last_veh_type",     NULL, NULL, NULL        },