Susan Lacy, who for decades was responsible for so many fabulous installments of the PBS series American Masters (Paul Simon! Mike Nichols! Jack Paar! Johnny Carson! Woody Allen! Edward R. Murrow!), has moved to HBO now. This means HBO now employs two of the best documentary producers in TV history, both of whom happen to be women (Sheila Nevins is the other). And tonight, it means Lacy, as director, presents Spielberg, a clip-filled look at the output, life, and impact of filmmaker Steven Spiel