feat: add world notifier

include/game/World.h

@@ -10,6 +10,8 @@
 #include "Mobs.h"
 #include "Team.h"
 
+#include "misc/ObjectNotifier.h"
+
 namespace td {
 namespace game {
 typedef std::pair<std::int16_t, std::int16_t> ChunkCoord;
@@ -123,10 +125,14 @@ public:
     virtual void OnArrowShot(MobPtr target, Tower* shooter){}
     virtual void OnExplosion(utils::shape::Circle explosion, float centerDamage, Tower* shooter){}
 
-    virtual void OnMobDamage(MobPtr target, float damage){}
+    virtual void OnMobDamage(MobPtr target, float damage, Tower* damager){}
+
+    virtual void OnMobDead(MobPtr mob){}
 };
 
-class World : public WorldListener{
+typedef utils::ObjectNotifier<WorldListener> WorldNotifier;
+
+class World : public WorldNotifier, public WorldListener{
 protected:
     TowerTileColorPalette m_TowerPlacePalette;
     Color m_WalkablePalette;