Implement requested changes

- Change the GuestPathfinder object to a smart pointer

 - Improved function signatures

 - Added javadoc comments to the abstract base class

 - Converted pointers to references in  pathfinding function calls

src/openrct2/entity/Peep.cpp

@@ -73,6 +73,8 @@ uint32_t gNextGuestNumber;
 
 uint8_t gPeepWarningThrottle[16];
 
+std::unique_ptr<GuestPathfinding> gGuestPathfinder = std::make_unique<OriginalPathfinding>();
+
 static uint8_t _unk_F1AEF0;
 static TileElement* _peepRideEntranceExitElement;
 
@@ -2357,7 +2359,7 @@ void Peep::PerformNextAction(uint8_t& pathing_result, TileElement*& tile_result)
 
         if (guest != nullptr)
         {
-            result = gGuestPathfinder->guest_path_finding(guest);
+            result = gGuestPathfinder->CalculateNextDestination(*guest);
         }
         else
         {