Strong typedef: Use strong typedefs for date, date tick, minutes types

Add delta types
Adjust/add type conversion functions
Add various utility methods on types
Remove the various minute macros
Fix some minute conversion inconsistencies

src/order_base.h

@@ -979,6 +979,6 @@ public:
 	inline const DispatchSchedule &GetDispatchScheduleByIndex(uint index) const { return this->dispatch_schedules[index]; }
 };
 
-void ShiftOrderDates(int interval);
+void ShiftOrderDates(DateDelta interval);
 
 #endif /* ORDER_BASE_H */