Codemirror 3.22.0

This adds CodeMirror 3.22.0

- `.min.js` downloaded from [CodeMirror compression helper](http://codemirror.net/doc/compress.html)
- includes `keymaps` and `addons` (absent in `3.21.0`)
- removing all html files

Selfishly, I really just want the json-ld mode, otherwise there are only a few changes.

Thanks.