“The fact is that, absent the two dots, most people would not trip over the ‘coop’ in ‘cooperate’ or the ‘reel’ in ‘reelect’ (though they might pronounce the ‘zoo’ in ‘zoological,’ a potential application of the diaeresis that we get no credit for resisting). And yet we use the diaeresis for the same reason that we use the hyphen: to keep the cow out of co-workers.”