refactor: separate mob ans world listener

include/game/Mobs.h

@@ -4,6 +4,8 @@
 #include "Types.h"
 #include "Team.h"
 
+#include "misc/ObjectNotifier.h"
+
 #include <vector>
 #include <memory>
 
@@ -218,6 +220,18 @@ MobPtr createMob(MobID id, MobType type, std::uint8_t level, PlayerID sender);
 std::string getMobName(MobType type);
 }
 
+class MobListener {
+public:
+    virtual void OnMobSpawn(MobPtr mob) {}
+    virtual void OnMobDie(MobPtr mob) {}
+
+    virtual void OnMobDamage(MobPtr target, float damage, Tower* damager) {}
+
+    virtual void OnMobTouchCastle(MobPtr damager, TeamCastle* enemyCastle) {}
+    virtual void OnMobCastleDamage(MobPtr damager, TeamCastle* enemyCastle) {}
+};
+
+typedef utils::ObjectNotifier<MobListener> MobNotifier;
 
 } // namespace game
 } // namespace td