There's a saying that imitation is the sincerest form of flattery – but not for Asus. The ZenBook 3 is the Taiwanese electronics firm's latest 12.5 inch MacBook-killing Ultrabook. It doesn't just so much imitate as it does completely destroy Apple's ultrathin laptop in specs and price.Weighing in at a scant 2 pounds and 11.9mm (0.46-inches) thick, it's...