Updating JSXGraph

Since the stack-js update, we have been able to use JSXGraph in its released form.

The files related to it are now stored under corsscripts/.

Download JSXGraph from here: https://github.com/jsxgraph/jsxgraph.

The files one needs to copy over are jsxgraph.min.css and jsxgraphcore.min.js, there is no need to copy the non minified versions.

The old STACK side jsxgraph.js that provided the stack_jxg features is now called stackjsxgraph.js and is being served from that same CORS-header tuning directory with that specific script. (Minification can be done using uglify-js:
npm install -g uglify-js
uglifyjs stackjsxgraph.js > stackjsxgraph.min.js.)

We do not apply Moodles or any other systems JavaScript processing on these, no need to run grunt or any such tool.

NOTE!

We really want to have a local JSXGraph copy instead of relying on a CDN version. We want to make it easy to run STACK in a closed network with no external requirements and having a local JSXGraph is one of the things we do to remove an external requirement.