MDL-46703 mod_data: limit the width of select element when editing templates

Thanks to Hittesh for the provided solution
MDL-46874 gradereport: replace usage of class hidden with dimmed_text
MDL-46887 mod_assign: Enforce module's maxbytes setting at submission.
MDL-46904 core_task: Gracefully handle rubbish entries in the tasks table.
MDL-46900 theme: allowed more than 1 nav collapse element
MDL-46923 core_behat: fixed typos in function names
MDL-46812 grade/report/grader: Need to tie up loose ends in Gradebook after MDL-43824

Squashed commit of the following:

commit 5881cccc95c135e1440ce0c5441a84b462941758
Author: Mary Evans <lazydaisy@visible-expression.co.uk>
Date:   Thu Aug 21 02:15:05 2014 +0100

    MDL-46812 grade/report/grader: Reset previous commit for left scroller.

commit 5abeb60470f02ab4c79c27b2a6f6187e75891e0b
Author: Mary Evans <lazydaisy@visible-expression.co.uk>
Date:   Thu Aug 21 01:29:41 2014 +0100

    MDL-46812 grade/report/grader: Added jsenabled css body class to rtl style.

commit a95d23d8b753a590d980e5427e8c74ba597c2b91
Author: Mary Evans <lazydaisy@visible-expression.co.uk>
Date:   Thu Aug 21 00:59:06 2014 +0100

    MDL-46812 theme_base; Removed more redundent CSS.

commit 3fb326e5b39738343e0b7c0d9c8da17adf5a09bb
Author: Mary Evans <lazydaisy@visible-expression.co.uk>
Date:   Wed Aug 20 13:24:59 2014 +0100

    MDL-46812 theme_base: Removed redundent grade/report/grader CSS in style/grade.css

commit c602e7e277f9ce1fed6d0eccf72c547432e130b6
Author: Mary Evans <lazydaisy@visible-expression.co.uk>
Date:   Thu Aug 14 12:50:14 2014 +0100

    MDL-46812 grade/report/grader: Need to tie up loose ends in Gradebook after MDL-43824

        1. fixed gradebook layout when JS is disabled
        2. added height and background color to scroller when JS is enabled
        3. removed redundent top margin in user-grades table
MDL-46880 mod_forum: move cron to scheduled task

Note that this is a very basic conversion without doing any refactoring
to split the tasks up better. That will come in MDL-44734, this is about
being a safe backportable change to give admins better control over the
running of the forum cron task.
MDL-46894 make Behat backup steps more robust.
MDL-46916 behat: improve question state test.
MDL-46918 ddl: fix error when renaming table already exists
MDL-46918 ddl: cover behavior with unit test
MDL-46917 atto: Focus on the editor when the form label is selected
MDL-46567 gradereport_history: Initial commit with basic structure of the report

Part of MDL-46191
MDL-46567 gradereport_history: Prevent duplicate username column from rendering

Part of MDL-46191
MDL-46567 gradereport_history: Fix bug with paging

Part of MDL-46191
MDL-46567 gradereport_history: Move paging implementation to db layer

Part of MDL-46191
MDL-46567 gradereport_history: Extra version.php info

Part of MDL-46191
MDL-46567 gradereport_history: Basic readme.md

Part of MDL-46191
MDL-46567 gradereport_history: Basic codestyle, phpdocs and other minor cleanups

Part of MDL-46191
This commit includes following changes:-
- Fix codestyle issues
- Remove readme file
- Fix and add file headers
- Fix and add missing phpdocs