CAutoMapper: Eliminate usages of const_cast

Same behavior, but makes it explicit from the interface that
modifications are clearly going on from within the class.

Runtime/World/CWorld.hpp

@@ -177,7 +177,9 @@ public:
   bool DoesAreaExist(TAreaId area) const;
   const std::vector<std::unique_ptr<CGameArea>>& GetGameAreas() const { return x18_areas; }
 
+  CMapWorld* GetMapWorld() { return x28_mapWorld.GetObj(); }
   const CMapWorld* GetMapWorld() const { return x28_mapWorld.GetObj(); }
+
   u32 GetRelayCount() const { return x2c_relays.size(); }
   CRelay GetRelay(u32 idx) const { return x2c_relays[idx]; }