Merge branch 'master' into jgrpp

# Conflicts:
#	.github/workflows/ci-build.yml
#	.github/workflows/codeql.yml
#	.github/workflows/release-linux.yml
#	.github/workflows/release-macos.yml
#	.github/workflows/release-windows.yml
#	src/map.cpp
#	src/music/midifile.hpp
#	src/order_cmd.cpp
#	src/order_gui.cpp
#	src/pathfinder/yapf/yapf_rail.cpp
#	src/pbs.cpp
#	src/saveload/afterload.cpp
#	src/saveload/saveload.h
#	src/saveload/vehicle_sl.cpp
#	src/script/api/script_text.cpp
#	src/ship_cmd.cpp
#	src/train_cmd.cpp
#	src/vehicle.cpp
#	src/vehicle_base.h
#	src/vehicle_func.h
#	src/vehicle_gui.cpp
#	src/vehicle_gui_base.h
#	src/viewport.cpp
#	src/waypoint_cmd.cpp

src/sl/vehicle_sl.cpp

@@ -427,6 +427,13 @@ void AfterLoadVehicles(bool part_of_load)
 				}
 			}
 		}
+
+		if (IsSavegameVersionBefore(SLV_VEHICLE_ECONOMY_AGE) && SlXvIsFeatureMissing(XSLFI_VEHICLE_ECONOMY_AGE)) {
+			/* Set vehicle economy age based on calendar age. */
+			for (Vehicle *v : Vehicle::Iterate()) {
+				v->economy_age = v->age.base();
+			}
+		}
 	}
 	si_v = nullptr;
 
@@ -806,6 +813,7 @@ SaveLoadTable GetVehicleDescription(VehicleType vt)
 
 		 SLE_CONDVAR(Vehicle, age,                   SLE_FILE_U16 | SLE_VAR_I32,   SL_MIN_VERSION,  SLV_31),
 		 SLE_CONDVAR(Vehicle, age,                   SLE_INT32,                   SLV_31, SL_MAX_VERSION),
+		SLE_CONDVAR_X(Vehicle, economy_age,          SLE_INT32,           SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_VEHICLE_ECONOMY_AGE)),
 		 SLE_CONDVAR(Vehicle, max_age,               SLE_FILE_U16 | SLE_VAR_I32,   SL_MIN_VERSION,  SLV_31),
 		 SLE_CONDVAR(Vehicle, max_age,               SLE_INT32,                   SLV_31, SL_MAX_VERSION),
 		 SLE_CONDVAR(Vehicle, date_of_last_service,  SLE_FILE_U16 | SLE_VAR_I32,   SL_MIN_VERSION,  SLV_31),