Merge remote branch 'remotes/origin/ocropus'

Merge remote branch 'remotes/origin/ocropus'

* remotes/origin/ocropus:
  Don't try full ocr, it's useless.
  change bebook optimisation to simple trim. still needs work.
  Fix issue where entire physical pages would disappear.
  Don't redo binarise if not needed.
  Do less with unpaper.
  Update docs, various fixes.
  ocropus as soon as possible