Of the thousands of people I have known or covered in the Massachusetts Legislature over the years, Steve Doran of Lexington would be the last I would have expected to wind up in prison. Last week Doran, 58, a former 14-year member of the House of Representatives, was sentenced to three years in prison after pleading guilty to drug charges. At one time, Doran had it all -- a lovely wife, four daughters, an extended family, a fine home, a solid reputation, good friends and an upwardly mobile political career. He threw it all away. What happened