Initial convertion of a_Dt to std::chrono

also refactored cWorld::m_WorldAge and cWorld::m_TimeOfDay

src/BlockEntities/MobSpawnerEntity.cpp

@@ -73,7 +73,7 @@ void cMobSpawnerEntity::UpdateActiveState(void)
 
 
 
-bool cMobSpawnerEntity::Tick(float a_Dt, cChunk & a_Chunk)
+bool cMobSpawnerEntity::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 {
 	// Update the active flag every 5 seconds
 	if ((m_World->GetWorldAge() % 100) == 0)