Resolve "Add Delete-Everything button"

Icon

I haven't added an icon, as I expect it's likely that this method will end up being moved into settings or somewhere similar

Bugfix

The clear method of the indexed db service wasn't working, the promise was never resolving. It took a while to figure out why, as there was no error message, but it was due to the request method being called with read permissions.

I added a try-catch block with a console.error call (for whatever reason it wasn't getting caught by the generic error handling), so that should it happen again it'll be quicker to diagnose

Closes #215 (closed)