Tweak logging for longer term measurements

I was using pokit to monitor the battery voltage of my 12V battery while camping - can watch it charge up during the day, and drop at night - all without having to dig into the battery box. I found though with logging that it was easy/confusing to restart a logging session, rather than just get the updated data. So this after a little tweak, eg an ‘are you sure’ to restart logging or just a bit harder to muck it up.