(svn r5934) -Cleanup: forgot some conversions to Year and to Date

-Cleanup: use _cur_year instead of _date for some (year based) comparisons
-Cleanup: remove a magic number in favour of another (less) magic number

depot.h

@@ -53,7 +53,7 @@ static inline bool IsDepotIndex(uint index)
  * within the given bounds. @see MIN_SERVINT_PERCENT ,etc.
  * @param index proposed service interval
  */
-static inline uint16 GetServiceIntervalClamped(uint index)
+static inline Date GetServiceIntervalClamped(uint index)
 {
 	return (_patches.servint_ispercent) ? clamp(index, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT) : clamp(index, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
 }