Three of the most outspoken and inventive plays at this year's fringe come from alumni of Warwick University fired up by recent student protestsThe best three pieces of theatre that I've seen so far at this year's Edinburgh fringe are Walrus theatre's Lemons, Lemons, Lemons, Lemons, Lemons, Breach theatre's The Beanfield and Barrel Organ's Some People Talk About Violence. All three are political pieces and each plays…