TO DO
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- Improve filtering mechanism
- Support for localized message templates


06/02/08 - 28/02/08
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Important sending API Improvements:
- Added messaging_message_send() to be able to send to non users and also for multiple sending.
- Now messaging_message_send_user() is just a wrapper for the previous one. It does $account to $destination translation.
- Reworked message rendering, so most plug-ins don't need to implement the render callback. Added more options.
- New method info properties: 
  'destination', field for getting destination from user account.
  'subject_glue', to glue multipart message subjects, [Optional]
  'send_user', callback for sending to users [Optional]
- The send callback should accept now a $destination array for bulk sending
Filtering improvements:
- Added a different filter for the subject
- Added support for drupal_html_to_text filtering. See http://drupal.org/project/html_to_text
- Performance: Filtering is done now only once for the whole text
Others:
- Some improvements for the settings page.
- Updated all contributed plug-ins accordingly.
- Improved logging by messaging_debug module.
- Fixed some other minor issues, added comments, etc..

- Added pgsql support (untested), by jaydub, http://drupal.org/node/223670
- Added 'administer messaging' permission.
- Split the debug functionality out of messaging and messaging_simple: messaging_debug module
- Fixed issues with messaging simple: http://drupal.org/node/218394