MDL-44359 fix explode(', ', regressions from MDL-44255
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.
MDL-43236 behat: Deprecate old steps

Correcting grammar errors and deprecating
the previous steps definitions:
- behat_data_generators::the_following_exists()
- behat_general::should_exists()
- behat_general::should_not_exists()
MDL-43236 behat: Updating references to deprecated methods
MDL-43236 behat: Step arguments normalization

Updating step definitions arguments according to the
documentation page.
Merge branch 'MDL-43236_master' of git://github.com/dmonllao/moodle
MDL-44440 behat: Changing , for > as a navigation tree nodes separator

Using greater than as seems a more natural separator
than the comma when separating nodes which have a
hierarchy relation.
Merge branch 'MDL-44440_master' of git://github.com/dmonllao/moodle
MDL-44017 Events: Deprecated content_viewed event

Replaced content_viewed event with appropriate events and deprecated
content_viewed event
MDL-44017 Events: Added unit test for report_viewed events