O2 Arena, LondonThe great master of observational comedy is back. This was Jerry Seinfeld's first show in the UK in 12 years, and he arrived in the midst of a live comedy boom in full swing: a country crazy for standup, crazy for "have you ever noticed … ?" and "what is it with … ?" " all those things of which Seinfeld is the supreme exponent.And he soon demonstrated his superb knack for hyper-inflating the impli…