MDL-40515: report_log: List activities in optgroups

Prevents users from generating reports on invalid values

Change-Id: If358fa06c8dadd33bb2875ea54ab4bce97b16aff
MDL-39489 behat: Updating to 2.6 moodlehq/behat-extension tag

Also solving new problem after Behat
2.5 upgrade.
MDL-38734: Automated backup failure causing all course to fail

Conflicts:
	backup/moodle2/backup_stepslib.php
MDL-42111 TinyMCE media preview: fix video preview display for TinyMCE media.

Effected themes: boxxie, clean, brick, formal_white and splash.
MDL-38664 Lesson mod: fixed re-attempt unseen page
MDL-38664 Lesson mod: code improvement for lesson re-attempt page
MDL-42453 theme_base: Fixed Error in base/style/admin.css that breaks CSS validator.
MDL-42464 mod_chat: Correct use of encoded & in link
MDL-42476 report_progress: don't browser sniff for SVG support

Use feature detection, its more robust and better practice.
MDL-42352 assignfeedback_editpdf - prevent scrolling when clicking on buttons
MDL-42482 assignfeedback_editpdf - prevent blank comments from disappearing when the menu is opened
MDL-42355 assignfeedback_editpdf - do not start a new comment immediately when deselecting the old comment
MDL-41251 forum_mod: add aria label and role to forum discussion page for accessibility purpose.
Thanks to Nate Baxley for creating the original patch.
MDL-42494 Fix workshop coding exception if all assessments have zero weight

If all assessments for the given submission have zero weight, the grading
evaluation plugin "Comparison with the best assessment" is unable to decide on
the average assessment as it ignores those with zero weight. In such rare case,
it makes sense to set the grading grade to null and prevent the coding
exception.
MDL-42402 EditPDF: CSS Improvements for editing toolbar.

The main change here is to prevent the default rendering of a select list for the page
selector, so that it looks more consistent with the rest of the toolbar on different
browsers/os combinations.

This is done with some vendor specific css rules targeting webkit, mozilla and ie.

There are also some minor tweaks to vertically align the images in the buttons and reduce the padding
above and below the toolbar.
MDL-42533 conditionlib: Field name is translated for students
MDL-42471 JavaScript: Adding missing dependency to toolbox
MDL-41041 portfolio: Temporary solution for event portfolio_send

As we have deprecated events_trigger(), the portfolio cannot use it
any more. Though there is no easy solution to get rid of this event
as it is used to register a cron job. MDL-42541 has been raised to
refactor the portfolio code to solve this problem. In the meantime
events_trigger_legacy() will be used.
MDL-42542 portfolio: Fix handlerfile in portfolio event handler
MDL-42517 testing Changed events test to use assertDebuggingCalled()