MDL-43369 : quiz statistics - average across attempts where item seen

and not across all attempts for subqs.
Merge branch 'wip-MDL-43800-m26' of git://github.com/marinaglancy/moodle into MOODLE_26_STABLE
MDL-43874 quiz, teacher comments should respect display options.

Whether the comments on manually graded questions were visible to
students should have been controlled by the 'Specific feedback' Review
option in the quiz settings. However, the quiz was not setting
$displayoptions->manualcomment, so it did not work.
Merge branch 'MDL-43581_26' of git://github.com/timhunt/moodle into MOODLE_26_STABLE
Merge branch 'MDL-43773-MOODLE_26_STABLE' of https://github.com/lucisgit/moodle into MOODLE_26_STABLE
Merge branch 'wip-mdl-43766-m26' of https://github.com/rajeshtaneja/moodle into MOODLE_26_STABLE
Merge branch 'wip-mdl-43765-m26' of https://github.com/rajeshtaneja/moodle into MOODLE_26_STABLE
Merge branch 'wip-MDL-43643-m26' of git://github.com/marinaglancy/moodle into MOODLE_26_STABLE
Merge branch 'MDL-43757_26' of git://github.com/dmonllao/moodle into MOODLE_26_STABLE
MDL-43797 lib/moodlelib.php: Remove custom homepages on user deletion

Change-Id: I43359a630c0b668ed3312828c15acc9cc220e49b
MDL-43797 lib/db/upgrade.php: Remove custom pages for deleted users

Change-Id: Ief5ec1dd0930e55b6f0bf2e0d2caa3febec07b18
Merge branch 'MDL-43874_26' of git://github.com/timhunt/moodle into MOODLE_26_STABLE
Merge branch '43688-26' of git://github.com/samhemelryk/moodle into MOODLE_26_STABLE

Conflicts:
	theme/bootstrapbase/style/moodle.css
Merge branch 'MDL-43246_26' of git://github.com/timhunt/moodle into MOODLE_26_STABLE
 MDL-43797 lib/db/upgrade.php: Optimise sql for my_pages deletion

Change-Id: Ibf8da394e3357fdde351eac49627539eb412e247
Merge branch 'm26_MDL-43797' of https://github.com/totara/moodle into MOODLE_26_STABLE
MDL-42928 JavaScript: Create a module to handle page scroll locking
MDL-42928 JavaScript: Add LockScroll to all modal dialogues
MDL-42928 JavaScript: Disable lockScroll for small chooserdialogues
MDL-39942: invite only users who can post to discuss