WHAT MAKES AN icon? What is good design? What are the criteria that lead you to believe an item is the very best a company has created throughout its long and successful history? We at Mac|Life don’t claim to have all the answers, but this feature aims to shine a light on the key products Apple has made since 1976 that still give us a giddy feeling in our tummies — and a handful of stinkers that leave us with an entirely different giddy feeling…