(svn r16694) -Fix [FS#2995] (rgradual loading, rnewindustries): only pay for whatever has been actually unloaded and perform the payment when unloading has finished. This fixes, amongst others:

* cheating by starting to unload and after getting paid rushing to the depot to get sold (or unloading, loading and getting paid again for the remainder)
 * cargo being dropped onto a station at the moment a stockpiling industry doesn't accept it anymore
 * industries getting cargo that has not been unloaded yet and subsequently dumping it back on the station in one go
Note: you will now get paid after the unloading has finished, so you'll have to wait a bit longer for 'your' money.

src/economy_func.h

@@ -34,7 +34,7 @@ void StartupIndustryDailyChanges(bool init_counter);
 Money GetTransportedGoodsIncome(uint num_pieces, uint dist, byte transit_days, CargoID cargo_type);
 uint MoveGoodsToStation(TileIndex tile, int w, int h, CargoID type, uint amount);
 
-void VehiclePayment(Vehicle *front_v);
+void PrepareUnload(Vehicle *front_v);
 void LoadUnloadStation(Station *st);
 
 Money GetPriceByIndex(uint8 index);