Log scale discoverability

Is it possible to make linear/log switching a bit more discoverable? Perhaps a `Log/Lin` button at the top of the graph?

I guess it's not bad at the moment (clicking the `(i)` and reading there helps). Personally I only discovered it by reading though all of https://github.com/haskell/criterion/issues/213, seeing it had been changed and the going and reading `(i)` knowing that it was possible (I'd become used to graphs where it wasn't an option)!

Of course this comes at the expense of more cluttered graphs and all that...