The launch this week of the brand new Lenovo Yoga Tablet range marks a new direction for Android tablet computers in general. The new devices, which come in 8 and 10 inch formats, may not offer many surprises in terms of architecture and performance, but they do feature some very cool features, including a ground breaking 18 hours battery life. We spend some valuable standby time putting the larger 10 inch Yoga Tablet 10 through its paces to bring you…