Support for importing settings from a local file

[redbmk]

When using a data image it seems very difficult to copy everything properly and paste it into the text field under "import". I usually get some kind of syntax error. Ideally there would be an option to select a file from the computer to get the data from there.

I have an idea how to do this I just tested by hacking around in Chrome's DevTools so I'll submit a pull request in a bit.