HTC's slogan is "quietly brilliant," and the company's living up to that reputation right now -- it snuck new details about its mystery handset right under our nose. What you see above are three screencaps from a banner ad running on the pages of Engadget even as we speak, hinting at an 8 megapixel imager, a sizable screen, and 4G video chat. Why, hello there HTC Thunderbolt / Mecha / Droid Incredible HD, and hurray for controlled