MDL-44630: Several additions to Common Cartridge Import/Export

Changes provided by Darko Miletic and Sam Chaffee.

* Fix problem with CC import not detecting a CC package. (Sam)
* Fixed Common Cartridge not importing FIB answers. (Sam)
* Fix to CC export so that short answer pattern matching question
  in a quiz does not prevent the entire quiz from exporting. (Sam)
* Fix notice about missing index when there is no answer-specific
  feedback in short answer question during CC export. (Sam)
* Fixed Japanese characters being incorrectly encoded (garbled)
  on Common Cartridge import. (Sam)
* Changed import of CC discussions to create 'Standard General'
  forums in Moodle. (Sam)
* Fix problem with question name being replaced with question
  text on CC import of exported Moodle questions. (Sam)
* Fix CC 1.1 multiple choice question import having no correct
  answers. (Sam)
* Fixed problem with multiple choice, multiple answers allowed
  questions not exporting correct answers to CC. (Sam)
* Removed duplicate method. (Darko)
* Implemented fix that skips quiz export if it contains
  non-exportable question. (Darko)
* Fixed: Common cartridge export is extremely slow when dealing
  with lot of more than 200 files. (Darko)
* Added support for basic roles support in common cartridge. (Darko)
* Implemented folder resource export. (Darko)
* Minor fixes to adjust to the standard. (Darko)
* Added support for exporting simple fill in the blank
  (shortanswer without wildcards in Moodle). (Darko)
* Added support for exporting essay question. (Darko)
* Added support for true/false export. (Darko)
* Added support for exporting multiple response questions,
  added also category information into question metadata
  during export (Darko)
* Added support for correctly importing multiple response
  questions. (Darko)
MDL-44630: Review changes

* Fixing coding style violations.
* Fixing DOMDocument warning.
MDL-42956 auth: Fix hard-coded LIMIT clause on keepalive_client method.
MDL-45359 JS: Only change mask zIndex on modal dialogues

When dealing with a non-modal dialogue within a modal dialogue, we should
not update the z-index of the underyling maskNode as it does not belong to
this dialogue.
MDL-43319 phpdoc: fix too much ham consumption by developers
MDL-45376 Completion: Form locking is still not working right

On submit of the form, it called 'freeze' on the completion-related
fields (even though they shouldn't have been frozen because you
already clicked the unlock button).
MDL-45382 atto_link: Missing context when finding anchors
MDL-45342 book: Automate MDLQA-2423 - A teacher can create book chapters and subchapters
MDL-44174 theme_clean: Updating information in readme file
MDL-45338 editor_atto: Check for selection changes on touch-based devices too
MDL-34904 lti: Fix notice while using lti in frontpage
MDL-45290 rubric: visual fixups

Fixed up visual issues with rubric editor on Clean.
MDL-45127 mod_lesson: Updated question edit screen with more help text.

Unless the custom scores is selected in the lesson settings the score section
in the question settings will be disabled. A help link has been added with
a description similar to this one.
MDL-45127 mod_lesson: Fixed reviewing lesson answers changing the lesson grade.
MDL-45127 mod_lesson: Behat test for reviewing a lesson.
MDL-45231 theme_clean: default navbar to absolute when running behat
Merge branch 'wip-MDL-45127-master' of git://github.com/abgreeve/moodle
Merge branch 'MDL-45382-master' of git://github.com/FMCorz/moodle
Merge branch 'MDL-45290-master' of git://github.com/jethac/moodle
MDL-45201 recent_activity: Fix set type notice in recent activity form