The deranged ex-Broadway dancer accused of shoving a retired Big Apple teacher to his death was indicted for murder Thursday night — hours after he flashed another carefree grin inside a Manhattan courtroom. Rhamell Burke, 32, cracked an ear-to-ear smile during a brief appearance Thursday as he faces decades behind bars for allegedly pushing retired Big Apple teacher Ross Falzone down a staircase and to his death at a Chelsea subway station on May 7. The serial troublemaker made a brief