nackport from HEAD

- Patch 13180 by chx: renamed check_query() to db_escape_string() and implemtented it properly per database backend.

  Read the manual for pg_escape_string:  "Use of this function is recommended instead of addslashes()." Or read sqlite_escape_string: "addslashes() should NOT be used to quote your strings for SQLite queries; it will lead to strange results when retrieving your data."

Tablesort used to output class=" active" for active columns with other properties (align="right"). Now it correctly uses class="foo active" if a class 'foo' was specified, and class="active" otherwise.

- Patch #10663 by JonBob: documentation improvements: fixed some typos and improved consistency to the use of Doxygen/api.module commands in the comments.

- Patch #9663 by jvandyk: the $i counter variable in tablesort_get_order() is unused and should therefore be removed.

- Patch #9657: more intelligent theme() function.  Hopefully, Adrian will be
  able to use this patch too.

- Patch #8603 by TDobes: added support for sticky forum topics to the blog
  and forum module.

- Patch #8617 by TDobes: changes all gifs to pngs for better consistency (and
  to get of proprietary formats).

- Added forum-sticky.png.  Made by Steven.

- Patch #6863 by Moshe: add 'class="active"' to the table elements of
  the active column.

- Patch #5744 by JonBob: tablesort does not call theme("image") correctly.

- Subset of patch 5613 by Goba: fixed some translation issues.

- Modified patch from pz: made tablesort.inc's validate.

- Fixed bug #5384: tablesort outputs invalid HTML (improved patch).

- Code improvements: changed some " to '.

- Bugfix: fixed SQL errors with tablesort when 'order' is invalid.
  Patch by Kjartan.  Fixes bug #2613.

- Usability improvements to the user module: removed some redundant menu
  items by taking advantage of the column sorting, added status messages
  and so on.  Patch by Moshe plus some fixes.

- Made the profile module use the table() function.  Patch by Moshe.

- Fixed breadcrumb spacing.  Patch by Moshe.

- Fixed colspan problem with node overview table.  Patch by Stefan.

- Fixed inconsistency with table sorting.  Patch 0122 by Al.

- Fixed problem introduced by partial integration of the administration pages.

- Fixed critical bug #2952: tablesort_init() used a static variable made it
  impossible to use more than one sortable table on a page.

- Don't use the global theme object; use theme() instead.

- Tested and committed Kjartan's performance patches.  (Fixed the access check
  in update.php though.)

- Made sure the 'Topic' title is only shown above the topics, not the icons.

- Automatically shorten the username when it is too long.  I implemented this
  as part of format_name() and could therefore nuke some code in the
  statistics module.  This is change is somewhat experimental and I'm willing
  to revert or change this if a number of people aren't too happy with this
  behavior.

- Left align the dates and authors: makes it easier/faster to scan.

- Made the little tablesort arrows clickable.

- Applied Moshe's tablesort patch!  Note that I changed the arrow images
  because those of Moshe where not identical.