Release 1.6:
- Adapt to safe strings, using mutable byte arrays where needed.

Release 1.5:
- Be resilient to changes in OCaml's hash table implementation.
- Added command "spamoracle upgrade" to convert the database to
  the current hash table format.

Release 1.4:
- More lenient rule for ignoring HTML comments.
- Recognition of S P A C E D  O-U-T words.
- Fixed a bug causing certain text-only e-mails to be ignored.
- Improved the "spamoracle test" command.
- Added "spamoracle words" command for troubleshooting the word-splitting
  algorithm.

Release 1.3:
- Better scanning of words in HTML documents.
- Better handling of multipart documents; now scan both text and HTML
  parts of a multipart/alternative.
- Support for Portuguese and Japanese (JIS encoding)
- Added configuration file (~/.spamoracle.conf) to allow twiddling
  with filtering parameters.
- Fixed database corruption problem with concurrent adds.
- Handles gzipped databases.
- Added manual pages.

Release 1.2:
- When choosing part of a multipart/alternative, ignore pure text part
  if much smaller than HTML part.
- Added commands "backup" and "restore" to facilitate future evolution
  towards other database formats.

Release 1.1:
- Fixed "usage" message.

Release 1.0:
- First public release.
