MDL-39286 Remove link on My Courses settings heading
MDL-41446 Completion: Incorrectly marks complete when grade data present with no actual grade
MDL-40939 tex filter: Changes to the TeX notation plugin

- Added configurable setting for path to mimetex binary
- Moved language strings from lang/en/admin.php to lang/en/filter_tex.php
- Config settings now stored in table config_plugins and retrieved
through get_config
- Added upgrade step to move TeX settings to the config_plugins table
and delete settings from the config table

AMOS BEGIN
  MOV [configconvertformat,core_admin],[configconvertformat,filter_tex]
  MOV [convertformat,core_admin],[convertformat,filter_tex]
  MOV [latexpreamble,core_admin],[latexpreamble,filter_tex]
  MOV [latexsettings,core_admin],[latexsettings,filter_tex]
  MOV [pathconvert,core_admin],[pathconvert,filter_tex]
  MOV [pathdvips,core_admin],[pathdvips,filter_tex]
  MOV [pathlatex,core_admin],[pathlatex,filter_tex]
AMOS END
MDL-32888 Grader report: added user search
MDL-32888 Grader report: refined user search
MDL-32888 Grader report: refined user search with no reset
MDL-32888 Grader report: cater for suspended students
MDL-32888 Grader report: use SESSION object and DB functions
MDL-32888 Grader report: Refined SESSION and api function use
MDL-42084 Core: Create new static class for use instead of set_time_limit
MDL-42084 Backup: Update time limit to avoid regression, use new class
MDL-42084 Core: Change set_time_limit to core_php_time_limit::raise everywhere

Exceptions (places where set_time_limit is still left) are:

Third-party libraries:
  ADODB
  PHPMailer

Moodle core:
  PHPUnit - not relevant (CLI mode)
MDL-42084 Unit tests: Remove unnecessary 'clear time limit change' lines
MDL-42184 bootstrapbase: popup should have no header
MDL-42808 library: Google API was resetting the timezone
MDL-42774 JavaScript: Ensure that shifter cleans build directories before running
MDL-42815 Backup/restore: Error saving files - log messages unhelpful

This commit contains three changes in the three files:
1. A bug in the backup process meant that anything logged after a
   certain point did not appear in the on-screen display of the
   backup log, because the logger was serialised and deserialised
   but display code referred to the old version. Changed so that
   code retrieves new object.
2. Add more information to backup log when there is a missing file.
3. Add more information to restore log when there is a missing file
   (and remove existing code duplication of the current message).

The 'missing file' situation is one that generally shouldn't occur in
normal usage, but when it does happen, it is useful to have full
information about the file.
MDL-42100 tool_capability: fixed incorrect links
MDL-41316 tool_spamcleaner: Fix sql queries

AS keyword is not allowed in sql qeries for table alias as Oracle doesn't support it
Thanks to Sara Cenni for suggesting the patch
MDL-42884 core_user: fixed issue when deleting users with invalid emails throws invalidusername exception