MDL-47975 assign: Stop gap fix for random time fails.
MDL-30968 mod/forum Fixed group link
MDL-48107 tool_monitor: added total subs to the delete rule string

Also made some minor language string changes.
MDL-48107 tool_monitor: prevent site rule removal when deleting a course
MDL-48107 tool_monitor: extended automated tests

Also adjusted them so they will pass with these changes.
Merge branch 'MDL-48107_master' of https://github.com/markn86/moodle
Automatically generated installer lang files
Merge branch 'install_master' of https://git.in.moodle.com/amosbot/moodle-install
Moodle release 2.8
weekly back-to-dev release 2.9dev
MDL-47391 Update pagelayout for default profile configuration
MDL-39692 grade: Ability to delete letter boundary
MDL-39692 grade: Little code clean up of letter boundary deletion
MDL-39376 enrol: Optimized setting for ldap and database
MDL-48156 task: Skip the scheduled task only for really disabled plugins
MDL-48093 HTML 5 video: Firefox now supports .mp4
MDL-48143 backup: Bump release to 2.9 dev branch
Merge branch 'MDL-48143' of git://github.com/stronk7/moodle
MDL-48144 upgrade: add v2.8.0 sep lines
MDL-48168 quiz editing: max grade should be editable after attempts

Note that there was a lot of legacy code left from Moodle 2.7 which is
no longer required, and I took this opportunity to delete it.