Initial convertion of a_Dt to std::chrono

also refactored cWorld::m_WorldAge and cWorld::m_TimeOfDay

src/BlockEntities/CommandBlockEntity.h

@@ -33,7 +33,7 @@ public:
 	/// Creates a new empty command block entity
 	cCommandBlockEntity(int a_X, int a_Y, int a_Z, cWorld * a_World);
 
-	virtual bool Tick(float a_Dt, cChunk & a_Chunk) override;
+	virtual bool Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk) override;
 	virtual void SendTo(cClientHandle & a_Client) override;
 	virtual void UsedBy(cPlayer * a_Player) override;