Shenzhen MacTop Electronics, a Chinese manufacturer, is now offering what it claims is a case for the second-generation iPad. Dubbed the “Crystal Case for iPad 2nd Generation,” the case appears to have different, slimmed contours than the first-generation model, with the opening around the speaker unusually big on the shell, and a hole for a rear-facing camera in the upper left-hand corner, similar to its position on the iPhone and fourth-generation…