#147640 by Jose A Reyero with further cleanup by myself: add language code to localization functions
This makes it possible to call these functions with a given language code when sending emails to multiple users with different languages in a request for example.

#145737 by yhager, documentation cleaned up by myself: add support for RTL CSS overrides and default RTL CSS override files for modules
Note: properties, which are different in the RTL display are marked with /* LTR */ in default CSS files now,
so maintainers remember that changing them should also have an effect on RTL CSS files.

This should open the way for better RTL (right-to-left written) language (such as Arabic and Hebrew) support.

#143249 by Jose A Reyero: add language parameter to t() to make it possible to retrieve translations of strings for different languages, to send emails to users in their own language for example

#127539: progressive operation support, refactoring update.php code to a generic batch API to support runnning operations in multiple HTTP requests
  - update.php is already on the batch API
  - node access rebuilding is in the works
  - automatic locale importing is in the works

 Thanks to Yves Chedemois (yched) for the good code quality, very wide awareness of issues related to batches,
 and the fantastic turnaround times. Hats off.

by Moshe Weitzman, webernet, chx, erdemkose and myself

- Patch #67893 by kbahey, dww, alienbrain, asimmonds et al: made it possible to filter log messages in the database log.

- Patch #137138 by jvandyk: fixed problem with drupal_http_request() not setting the proper error code when a network effect occurs.  Causes the XML-RPC backend to fail.

- Patch #131419 by Chris Johnson: renamed the error handler to avoid conflicts with third-party applications.

- Patch #34755 by chx et al: faster menu system.  HEAD is temporary broken and there is no upgrade path yet.