Sundance will also give a megaphone to Tim Sutton, who wrote and directed ''Dark Night,'' a drama inspired by the Aurora, Colo., movie theater massacre in 2012, and Kim A. Snyder, whose ''Newtown'' examines the continuing community trauma caused by the 2012 mass shootings at Sandy Hook Elementary School in Connecticut. Part of Ms. Snyder's harrowing documentary looks at how little has changed in regard to gun reform.