Initial convertion of a_Dt to std::chrono

also refactored cWorld::m_WorldAge and cWorld::m_TimeOfDay

src/BlockEntities/BlockEntity.h

@@ -110,7 +110,7 @@ public:
 	virtual void SendTo(cClientHandle & a_Client) = 0;
 	
 	/// Ticks the entity; returns true if the chunk should be marked as dirty as a result of this ticking. By default does nothing.
-	virtual bool Tick(float a_Dt, cChunk & a_Chunk)
+	virtual bool Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 	{
 		UNUSED(a_Dt);
 		return false;