* fix the build warnings (-Wformat=2)
* Support add_doc_file, set_doc_files, get_doc_files, _slang_doc_dir from
  slang.
* Design a Debian specific jed.rc file for doc/jed/examples/
  (or several ones).
* complete (and fix) the NEWS file to inform the user about updates since
  0.99.16-6