Also fixing a missing capability checking.

Signed-off-by: Yuliya Bozhko <yuliya.bozhko@totaralms.com>

When a teacher edits an entry in the database module
it would change the group ID to the one that the teacher
currently had selected.

Thanks to Steve Bond for providing a patch.

Conflicts:
	admin/tool/monitor/edit.php
	admin/tool/monitor/lang/en/tool_monitor.php

Conflicts:
	mod/forum/version.php
    mod/forum/db/upgrade.php

When the rule plugin is not a module you can subscribe
to it without having to select to which module instance
you want to subscribe, so there is no need to display
a drop down menu.

Conflicts:
	version.php

An event that has already contributed to a notification should not contribute to another notification for the same subscription.
This needs to be done so we do not overwhelm the user.