MDL-42573 skydrive: support non-js login scheme

This is actually not especially useful because Microsoft don't currently
support non-JS login. But its possible they could make it work in
future. And at least the user gets an error from MS rather than blank
screen.
MDL-41232 revert IE8 fix for solving unspoken filemanager details on View List selection
MDL-42598 quiz variant randomisation not random enough.

A student would get the same question variants (for example for a
calculated question) on their first attempt at both copies of a
duplicated quiz.
MDL-33536 navigation: hide hidden categories from the navbar
MDL-42215 lang: improved the help string for fullnamedisplay
MDL-42683 EditPDF: stamp picker button size is wrong
MDL-42624 Clean theme: dialog should be displayed above the header for user experience purpose
MDL-42690 mod_assign: remove submit button from single grading interface
MDL-42710 course: management cat sorting perfecting taking place
MDL-42719 course: management view mode wrap fixed
MDL-40481 quiz responses report needs cols need text_sorting
MDL-42728 Merge English strings from the en_fix language pack
MDL-42666 repository_boxnet: Convert repository to APIv2
MDL-42666 repository_boxnet: Function to convert APIv1 references to true copies
MDL-42666 repository_boxnet: Tool to launch the migration
MDL-42666 repository_boxnet: Advise the user to run the migration tool
MDL-42666 repository_boxnet: Disabling file references
MDL-42666 repository_boxnet: Remove hardcoded date for APIv1 end of life
MDL-42666 oauthlib: Getter methods for accesstoken, client id and secret
MDL-42666 repository_boxnet: Revoke access token when logging out