This adds a fragment requirements class to allow plugins
to register JavaScript to be used in an mform.

Otherwise we would need to unescape href and title.

John Okely authored Jan 29, 2016 and David Monllaó committed Jan 29, 2016

Also:
* In behat, ensure nav node exists before checking attribute (Credit to
  Rajesh Taneja)
* Remove some unused JS constants
* Fix debugging notice for users without settings block

Ryan Wyllie authored Jan 28, 2016 and David Monllaó committed Jan 29, 2016

Fixed up the left/right keyboard navigation to match
the aria specification. Also stopped the root node from
being collapsible.

Switch from custom id references to the element's id attribute.

Extra fix to get rid of an unnecessary call to getValidationScript().

I noticed we do not need to list the names of potentially affected
reviewers. If the user (teacher) has the capability to see other
assessments (which they do in 99%), the list of assessments is displayed
at the confirmation page anyway. If for some reason they do not have the
capability, we should not list the names.

The second fix is that the action buttons (such as Delete or Edit) are
not displayed on the removal confirmation page.

And finally, as the output->confirm() wraps the message with implicit
<p>, it is not valid to pass HTML with any block elements. So instead of
concatenating the two messages, we simply define a new string for this
situation.