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-44575: Prevent cron from sending feedback notifications when assignments are hidden in the gradebook
MDL-44630: Review changes

* Fixing coding style violations.
* Fixing DOMDocument warning.
MDL-45210: Fix broken link when plagiarism plugins are disabled
MDL-45232: mod_data: Simultaneously added entries do not sort correctly

This was picked up by behat on a fast machine, when using shorter polling interval.
MDL-45239 editor_atto: The editor cannot be active if it is not the active element

FireFox thinks that you can have an active selection on an element which
currently does not have focus. How this can be the case is a mystery.
MDL-42869 calendar: HTML validation check fails on add event screen
MDL-45080 fix question_category_created url and legacy log data
MDL-45254 atto_equation: Allow insertion of macros at the beginning of words
MDL-44004 grading_rubric: Ensure that score is set before using it
MDL-45090 explain event->courseid
MDL-44398 tags: Fix incorrect usage of caps
MDL-45260 Memcache session support does not work for multiple servers
MDL-44730 core_install: reduced the width of the buttons on the first few screens of the installer so they sit side by side
Merge branch 'MDL-44730_install' of https://github.com/andyjdavis/moodle
Merge branch 'w17_MDL-45080_m27_questioncreate' of https://github.com/skodak/moodle
Merge branch 'MDL-42869' of https://github.com/danielneis/moodle
MDL-45250 add debugging message to deprecated add_to_log()
MDL-45268 behat: tests for participants block
MDL-45280 wrtie default value for admin_setting_configstoredfile

this fixes regression from MDL-45134