nypost.com — MOVIE REVIEW THE RAVENE.A. Poe, serial-killer hunter. Running time: 112 minutes. Rated R (gore, violence). At the E-Walk, the 19th Street, others. 'But I'm only a critic!'' exclaims a victim who's about to be sliced up by a pendulum operated ax in "The Raven,'' a thriller that posits-more entertainingly than convincingly - that Edgar Allan Poe spent the last five days of his life tracking down a serial killer inspired by his tales of terror.