Issue #2342667 by claudiu.cristea, Dave Reid, ndobromirov: Cron and batch processing of queues are not accepting callables

- Patch #1089472 by janusman, David_Rothstein: batch API finishes when >99.5% of items have been processed.

- Patch #600836 by tim.cosgrove, dww, naxoc: batch API never terminates if you set ['finished'] > 1.

- Patch #756762 by effulgentsia, fago, sun, rfay, pwolanin: AJAX should follow same rules for whether to call drupal_rebuild_form() as non-AJAX submissions.

#710142 by Berdir, moshe weitzman, chx: Handle exceptions in shutdown functions (with tests). Hopefully the last of these weird 'Stack frame in Unknown line 0' errors.

#552478 by pwolanin, samj, dropcube, and sun: Improve link/header API and support on node/comment pages rel=canonical and rel=shortlink standards.

#610204 by effulgentsia, Gábor Hojtsy, sun, Damien Tournoud and ksenzee: API changes to support overlays: lays ground work for implementation.

- Patch #572618 by effulgentsia, pwolanin, sun: all theme functions should take a single argument. Code clean-up and performance improvement. Woot.

- Patch #555762 by gordon, sun | yched, chx, moshe weitzman, KiamLaLuno, lilou: improvements to batch API.

- Patch #556018 by Damien Tournoud, dereine | sun: rename drupal_to_js() and drupal_json() for consistency and readability.

Patch #579366 by sun, litwol | chx, Dries: simplified form API redirection handling. I can actually understand it now. ;-).

#372563 by cytefx: Rename drupal_set_html_head() to drupal_ADD_html_head() which actually describes what it does.

- Patch #201122 by c960657, Moshe Weitzman: never write anonymous sessions, unless something has been written to . This is an important performance improvements -- as long as you use modules that use  carefully. It might be good to report some analytics about this in the performance settings page so administrators can see if there is a 'broken' module.

- Patch #243773 by chx, catch, boombatower, yched, dmitrig01, et al: use the batch API for running the tests instead of an all-in-one approach.  Great work.