CodeWorld web site update

[Chris Smith]

I've just pushed a new release of CodeWorld at www.codeworld.info.  There aren't a lot of very visible changes, but a few things to keep an eye on...

1. GHCJS has been updated to its current version.  I spot checked and everything seems to work fine.  Let me know if anything is suddenly broken.

2. There's now a landing page at www.codeworld.info, and you'll have to click through to get to the editor.  If this bugs you, just bookmark codeworld.info/env.html

3. CodeWorld now redirects to HTTPS.  This was done just on general principle: even though nothing in CodeWorld is really sensitive, for privacy reasons all web sites ought to be using HTTPS these days.

Any feedback on improving the new landing page is definitely appreciated.  I just wanted something there with links to the textbook, an introduction, etc.