Almost like clockwork, shortly after the release of a new Apple portable product, a relatively young company appears on the scene with a modular case system designed to be paired with a variety of different attachments. Mophie did it with the first video-ready iPod and iPod nano back in 2006, companies such as Gizmac and Barefoot Innovations have done it with various iPhones, and now a company called ModulR is trying it with the iPad. The core of…