ABU DHABI (Reuters) – Nokia unveiled its first tablet and two massive-screen smartphones, referred to as phablets, at the annual Nokia World event in Abu Dhabi on Tuesday. The Lumia 2520 tablet, along with its Lumia 1520 and 1620 phablets, are among the ultimate merchandise the Finnish firm developed to compete with Apple and Samsung earlier than determining to sell its handset industry to Microsoft. The brand new Lumias use Microsoft’s Windows Phone operating system and will face tricky competition from large-display smartphones from Samsung and Apple, which can also be anticipated to unveil slimmer, faster iPads on Tuesday. …