If you want to get documents, photos, songs and other data neatly organized on your Lumia smartphone, Microsoft is developing a file manager tool for Windows Phone 8.1, the next version of the mobile OS currently available as a pre-release developer preview. The announcement was made by Joe Belfiore, a corporate vice president with the Windows Phone group, during a Reddit AMA (Ask Me Anything) session Friday, during which he made generous use of all-caps words and exclamation points.