MDL-43266 Testing sites are cleaning all test dataroot contents
MDL-44095 frontend: fix typos in readme file
MDL-44334 Javascript: Prevent scroll locking for small screen heights
MDL-44451 fix plugin_misplaced_exception exception
MDL-44061 Ajax: Log whitespace issues to the server error log
MDL-44345 repository_youtube: Endless loop when reaching last results
MDL-43721 Assign: Static cache for plugin is_enabled and is_visible because they get used alot
MDL-43721 Assign + groups: Improve performance of assign grading table

Add a function to the groups lib to filter a list of users down
to the ones who can see the module. Required because calling
groups_course_module_visible() for a list of users is too slow
and we shouldn't spread group logic outside of grouplib.php.

Using it in the assign grading table reduces DB queries from 6198/1 to 256/3.

This is 12secs down to 2.5secs.
MDL-44480 Javascript: Correct dialogue ID generation
MDL-32699 wiki: only edit capability is required to restore wiki revision
MDL-40721 wiki: missing page->set_url() when restoring wiki
MDL-44337 glossary: behat test for glossary categories
MDL-44471 Revert "MDL-42238 mod_wiki: Alternate name sql update to wiki_print_recent_activity"

This reverts commit 6d3d9bd927d5386b1dc4fbbcb7db5559efa7a5cd.
MDL-42870 completion: show failed activities as incompleted
MDL-42368 Themes: Anomaly breadcrumb fix

Previously the editing button could become unreachable with small window
sizes.
MDL-44440 behat: Log out compatible with clean

.navbar needs to be clicked before following
log in or log out links.
MDL-44440 navigation: Added behat step to navigate from navigation/Admin block

This step will help navigate to different parts of moodle
using navigation or adminstration block.
MDL-44440 behat: Other fixes to make clean work properly

- Update the step to follow links inside a treeview
  to work also when JS is disabled.
- Make regions accept header and footer.
- Change some locators refering to non-clean compatible
  regions.
- Restricting click to the table row in forum tracking
  because seems to conflict with the navigation bar when
  using narrow window sizes.
MDL-44440 behat: Refactoring features to use I navigate to

Replacing multiple "I expand node" steps by the
new "I navigate to". Also fixing few I navigate to
when dealing with non-JS.
Moodle release 2.6.2