Refactoring and improvements of the accesslib.php library including prevention of access for not-logged-in users when forcelogin enabled, improved context caching, OOP refactoring of contexts, fixed context loading, deduplication of role definitions in user sessions, installation improvements, decoupling of enrolment checking from capability loading, added detection of deleted and non-existent users in has_capability(), new function accesslib test, auth and enrol upgrade notes.
More details are available in tracker subtasks.
These are the changes from MOODLE_13_STABLE, merged into trunk
The tag MOODLE_13_MERGED on the MOODLE_13_STABLE branch now refers to this point
The biggest changes here are the fixes for HTML editor in all standard modules