Screen of Consciousness
 An Amusement Column     by Harry Haun  THE SHORT-CUT LANE: Apparently, Nathan Lane is shopping around for shorter shows. His most recent Broadway opus"Taylor Mac's Gary: A Sequel to Titus Andronicus"was a start, tipping the scales (sans intermission) at a scant and snug 90 minutes. The play(s) before that"B.G.: Part One and Part Two of Tony Kushner's epic cavalc…