He’s the Felix Unger of Beacon Hill. Like the fastidious half of The Odd Couple, House Speaker Robert DeLeo has a severe allergy. One whiff of anything that could be construed as a tax increase – no matter how tenuous the claim, or how sensible and popular the measure – and the Speaker starts honking. The latest imagined allergen to fall victim to his hypochondria? A measure to end a tax exemption for soda.