The West Marin Players make a major departure from Gilbert & Sullivan’s Victorian England with this year’s music production, Frank Loesser’s 1956 Broadway gem, “The Most Happy Fella.” Showing at the Dance Palace Community Center from July 10 to 12, this exhilarating musical is the set in the Napa Valley in 1927. It’s the tale of a May-December romance involving a  middle-aged grape rancher who, through letters, shyly woos a young San Franciscan waitress who…