Choose your aphorism: "Insanity is doing the same thing over and over again and expecting different results" or "Those who fail to learn from history are condemned to repeat it." Either of these will help you to understand Dick Wheeler, the exasperating mess of a middle-aged manboy at the center of Tracy Letts's smart and witty, if annoyingly repetitive dramatic comedy Linda Vista, opening tonight at the Helen Hayes Theater. . . .