0.18.0

Added

• Per-chapter artwork — a small number of enhanced audiobooks embed a
  unique image for each chapter (Apple's chapter-artwork convention, mostly
  seen on podcasts and a handful of audiobook productions). Midnight
  Athenaeum now detects this, caches each chapter's image, and shows it as a
  thumbnail in the chapter list — the mini-player and Windows media flyout
  also switch to the current chapter's art while it's playing, falling back
  to the book cover otherwise. Books without this (the vast majority) are
  completely unaffected.