Crest Nicholson has made a strong return to the stock market, announcing a 76% rise in pre-tax profit to £28.1 million over the six months to April 30th 2013, and a climb in operating profit margin from 15.7% to 18.1%. The company's open market legal completions increased 30% to 699 against 537 over the equivalent period in 2012. Sales rates …