Kobo has revealed its latest premium ereader and it has the largest e-ink screen you can buy right now.The Kobo Aura One boasts a 7.8-inch screen - most ereaders are currently 6-inch options - a waterproof design and access to Kobo's store of five million titles. Even though the screen has been increased in size it still has a pixel density of 300 pixels-per-inch...