Add setting: station rating waiting time tolerance depends on cargo class

src/settings_type.h

@@ -604,6 +604,7 @@ struct StationSettings {
 	bool   never_expire_airports;            ///< never expire airports
 	byte   station_spread;                   ///< amount a station may spread
 	byte   catchment_increase;               ///< amount by which station catchment is increased
+	byte   cargo_class_rating_wait_time;     ///< station rating tolerance to time since last cargo pickup depends on cargo class
 };
 
 /** Default settings for vehicles. */