Add ability to refresh directory in photorec

[JohnVeness]

In photorec, when selecting a destination to save the recovered files to, it would be nice if there was a quick way to refresh the shown listing (e.g. by pressing R).

I got to that point in a recovery, realised I wanted to create a new directory so did that in another terminal, but the new directory wasn't listed in photorec. I had to navigate into another directory (e.g. "..") and back again for the new directory to show up.

It's not a massive problem, just a small papercut that would be nice to fix :)