MDL-46235 ddl: add support for large number of text fields in one database table
MDL-47183: viewhiddenactivities should use the module context

Thanks to Paulo Matos for the forum part of this change.
MDL-46712: Center EditPDF window on browser resize / zoom
MDL-41593 admin: use default setting if preventexecpath active

This resolves problems when installing Moodle
and addons when preventexecpath active.

Please note the admin_setting_configfile is still
incorrectly restricted - this will be resolved by
MDL-40949.
MDL-47572 libraries: modify unittest to avoid random timing fail

Thanks to Nigel Cunningham
MDL-47583 tinymce_managefiles: correctly decode filename
MDL-47583 atto_managefiles: correctly decode filename
MDL-47585 stats: fixed incorrect user dropdown
MDL-44548 mod_scorm: force an external sync to check for updated files.
MDL-47594 core_accesslib: removed three useless lines of code
MDL-47613 wiki: allow searching several words

Thanks to Sandeep B for suggested solution
MDL-47555 core_availability: Issue with page layout & grade restriction

* Set pagelayout before getting section info, otherwise conditional activity renderers will default to the default 'base' layout.
MDL-47631 report_participation: fixed filtering by letter
MDL-46546 gradebook: Grade import gives error on bad csv upload.
MDL-47646 CURL redirect unit test: handle broken servers
Automatically generated installer lang files
MDL-46151 cachestore_memcache: now checks extension version for support
MDL-46235 Admin: Fix typos in mysql_compressed_rows.php cli script
MDL-46546 core_grades: Move error checking after csv load.
MDL-38732 gradereport_grader: Handle simultaneous graders