Upgrade MathJax to 2.7 (when it's released) for Moodle 3.2 release

(Simey to add additional testing instructions for upgrade here, don't pass without them ) Thanks Dan Upgrade test Before upgrade (you can tweak the version number down and run mdk version.php in a separated branch) Check out the settings at Site administration ► Plugins ► Filters ► MathJax. Make sure that the url for https is https://cdn.mathjax.org/mathjax/2.6-latest/MathJax.js Search for the setting httpsurl on the database, on mdl_config_plugins Please note that value Now, do version bump and run upgrade. Check out the settings at Site administration ► Plugins ► Filters ► MathJax. Make sure that the url for https is https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js Search for the setting httpsurl on the database, on mdl_config_plugins again. PLEASE MAKE SURE now, the value for that field is https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js . Regression test MathJax is enabled by default, but if not go to Site administration ► Plugins ► Filters ► Manage filters. Activate MathJax. Make sure that your html editor has an equation editor enabled: Home ► Site administration ► Plugins ► Text editors ► Atto HTML editor ► Atto toolbar settings. Check out the settings at Site administration ► Plugins ► Filters ► MathJax. Make sure that the url for https is https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js Go to a course. Create a page and create some math equations with the equation editor. Make sure that there are no JavaScript errors. Save the page and view it. Check that the filter works and that the equation is shown. Enable the TeX filter and test from point 4 onwards to make sure that the TeX filter has not been affected.