Basic implementation of jsoneditor (https://github.com/josdejong/jsoneditor)
Bundled version (bundle_jsoneditor.html) can be used as a standalone file in a browser, or the main page (jsoneditor.html) can be hosted by a server.
Adds:
- simple file importing/exporting
- a warning when leaving the page after changing data
- a cookie to remember what mode was last used