- Patch #16358 by James: added toolkit to enable better image handling.  The avatar code and the upload module have been updated to take advantage of the new image API.

There are 5 main functions that modules may now utilize to handle images:

* image_get_info() - this function checks a file.  If it exists and is a valid image file, it will return an array containing things like the pixel dimensions of the image, plus the 'type' and common extension.
* image_scale - resizes a given image to fit within a given width / height dimensions, while maintaining aspect ratio (not distorting the image).  This function can be used to generate thumbnails, or ensure a maximum resolution, etc.
* image_resize - similar to image_scale (but will not respect aspect ratio - may well distort the image).
* image_rotate - rotate an image by X degrees
* image_crop - crops an image to a given rectangle (defined as top-left x/y coordinates plus a width & height of the rectangle).

Contribution modules will now be able to rely on these base manipulation functions to offer additional functionality (such as image nodes, photo galleries, advanced image manipulation, etc).

- Patch #16513 by James (slightly modified): export categories and enclosures to RSS feeds (and made RSS feeds extensible).

  NOTE: this needs to be documented.

- Patch #10425 by ccourtne and walkah: added admin screens to maintain forums instead of forcing the user to add a taxonomy.

- Patch #6847 by Gerhard: replaced vocabulary->nodes by a separate table and tidied up the taxonomy API a bit.  This fixes a number of issues.

- Patch #13020 by chx: let Drupal handle multiple database layers.

- Removed the PEAR database backend.  It's no longer being used/maintained.

- Made the ping module ping pingomatic.com, which in turn, will ping all the major ping services.
  Less code to ping more services.

   * Less logic in theme code.
   * Encourages use of the menu system.
   * Easier to find where a title or breadcrumb comes from in other people's code because there are less places to look. Look in menu and then grep for the appropriate set function. Looking for calls to theme_page() is hard because there are too many of them.
   * Very slightly more efficient.

- Added a simple contact module to core.

  changes are:

  1. Simplified the statistics pages: there are less pages and on the
     remaining pages there is a lot less visual clutter (less columns and
     better presentation).

  2. Reorganized the 'administer - logs' menu: flattened the menu structure
     and removed a number of links.

  3. Improved performance.  Most statistics pages used about 160 slow SQL
     queries which made the statistics pages fairly unusable on my system.
     The new pages use at least 10 times less SQL queries and render much
     faster.  They are actually usable.

  4. There is now a 'track'-tab on node pages, and a second subtrab on the
     user accounts 'track'-tab for people with the 'access statistics'
     permission.  They can be used to resp. track the node and the user.
     This makes the statistics more accessible.

  5. Changed the way watchdog messages are filtered.  This makes it easier
     to introduce new watchdog types.

  6. Reworked the statistics module's permissions.

  7. Less code: 223 insertions(+), 343 deletions(-).

  8. Fixed several glitches: for example, the statistics pages sorted the
     'Name' column by user ID instead of by name.  Unfortunately, it is
     too difficult to backport these to DRUPAL-4-5.

  TODO:

  1. Review the statistics modules help pages.

  2. Help fine-tune the interfaces/views.

  NOTES:

  1. You'll want to run update.php.

    + added support for multi-site configurations.
    + tidied up some old cruft and added code comments.

- Added generic flood control mechanism to throttle certain operations per hostname (eg. posting comments, requesting passwords, sending e-mails).  See flood_register_event() and flood_is_allowed() for details.

  * There are only two throttle levels instead of 5, namely 'enabled' and 'disabled'.  This makes it a _lot_ easier to predict when the throttle will kick in.  However, if you maintain a module that is throttle-aware, it needs to be updated!

  * The throttle mechanism now uses the current number of anonymous users or the current number of authenticated users to kick in.  This is a _lot_ more intuitive than the old throttle mechanism.

  * The throttle block has been removed -- you can now use the "Who's online" block to determine the good throttle settings.

  * Most of the documentation has been removed because it was deprecated.

  * It's less code!

1) Clean up the text analyser: make it handle UTF-8 and all sorts of characters. The word splitter now does intelligent splitting into words and supports all Unicode characters. It has smart handling of acronyms, URLs, dates, ...

2) It now indexes the filtered output, which means it can take advantage of HTML tags. Meaningful tags (headers, strong, em, ...) are analysed and used to boost certain words scores. This has the side-effect of allowing the indexing of PHP nodes.

3) Link analyser for node links. The HTML analyser also checks for links. If they point to a node on the current site (handles path aliases) then the link's words are counted as part of the target node. This helps bring out commonly linked FAQs and answers to the top of the results.

4) Index comments along with the node. This means that the search can make a difference between a single node/comment about 'X' and a whole thread about 'X'. It also makes the search results much shorter and more relevant (before this patch, comments were even shown first).

5) We now keep track of total counts as well as a per item count for a word. This allows us to divide the word score by the total before adding up the scores for different words, and automatically makes noisewords have less influence than rare words. This dramatically improves the relevancy of multiword searches. This also makes the disadvantage of now using OR searching instead of AND searching less problematic.

6) Includes support for text preprocessors through a hook. This is required to index Chinese and Japanese, because these languages do not use spaces between words. An external utility can be used to split these into words through a simple wrapper module. Other uses could be spell checking (although it would have no UI).

7) Indexing is now regulated: only a certain amount of items will be indexed per cron run. This prevents PHP from running out of memory or timing out. This also makes the reindexing required for this patch automatic. I also added an index coverage estimate to the search admin screen.

8) Code cleanup! Moved all the search stuff from common.inc into search.module, rewired some hooks and simplified the functions used. The search form and results now also use valid XHTML and form_ functions. The search admin was moved from search/configure to admin/search for consistency.

9) Improved search output: we also show much more info per item: date, author, node type, amount of comments and a cool dynamic excerpt à la Google. The search form is now much more simpler and the help is only displayed as tips when no search results are found.

10) By moving all search logic to SQL, I was able to add a pager to the search results. This improves usability and performance dramatically.

- Updating the date.

- Added a note about PostgreSQL no longer depending on PEAR.

- Added small note about PHP5 compatibility.