MDL-43639: Prevent user updated event on every login

If auth plugin prevents local passwords, then user
is updated and event is triggered on every login.
MDL-46633 chat: Chat send button gets stuck
MDL-45952 feedback: non-respondents in groupings

Fixes feedback non-respondents list to show only members in groups in
the selected grouping if "Available for group members only" is selected.
MDL-46979 backup: remove duplicate string.

Thanks to Matt Sammarco for spotting this.
MDL-45909 install/css: Left align input form fields on Install pages, in RTL mode
Merge branch 'MDL-43639_updatePassEveryLogin' of https://github.com/moodlerooms/moodle
Merge branch 'MDL-45909_install_master' of https://github.com/nadavkav/moodle
Merge branch 'MDL-46979' of git://github.com/timhunt/moodle
Merge branch 'MDL-46633' of https://github.com/shashirepo/moodle
Merge branch 'MDL-45952_master2' of git://github.com/Syxton/moodle
MDL-46619 Forum: only output last poster's name if user can view it.
MDL-46619 Forum: link to the discussion only if users cannot see posts.
MDL-47052 report_participation: fixed bug when filtering by first letter
Merge branch 'wip-MDL-47052-master' of git://github.com/marinaglancy/moodle
MDL-44725 Availability: Replace groupmembersonly - upgrade, core (1)

* Upgrades existing data so that the groupmembersonly option is
  replaced with equivalent data for the new availability API.
* Removes the database field and admin setting used for
  groupmembersonly.
* Changes core modinfo library to remove/deprecate groupmembersonly
  data and functions.
* Changes other core library files to remove groupmembersonly
  references.

Includes deprecation of several functions, listed in lib/upgrade.txt.
MDL-44725 Availability: Replace groupmembersonly - core_availability (2)

Remove groupmembersonly usage in the core_availability API, and change
the update code (used in backup) so that it considers groupmembersonly
when restoring old backups.
MDL-44725 Availability: Replace groupmembersonly - backup (3)

Change backup and restore to not include the field, and to cope
correctly with 2.6 (and before) and 2.7 backups.
MDL-44725 Availability: Replace groupmembersonly - forms (4)

Remove groupmembersonly option from module editing forms.
MDL-44725 Availability: Replace groupmembersonly - login (5)

Remove groupmembersonly option from require_login.

NOTE: This code, and another branch (both related to login when
accessing activities on the site course), are not actually
necessary because there is code above which already checks
$cm->uservisible.

NOTE: You can see this change more simply by doing
git diff --ignore-space-change; indent was altered.
MDL-44725 Availability: Replace groupmembersonly - FEATURE_xx (6)

Remove old FEATURE_GROUPMEMBERSONLY as no longer required.