I'm about to get a new Mac. My current system is the result of several generations of migrations from Mac to Mac over many years. Along the way it has accumulated plenty of unused system/preference files and folders for apps and things that I no longer have. Is there an app out there that can identify these things and help to clean them out? If I can help it, I'd rather not move all of the old excess baggage over to the new machine with me, but I don't want the pain in the ass of installing and setting everything manually.