Either all files or manual selection

- Do analyze all image folders, we have to trick with the logging, since
  it otherwise all goes to one file. Implementing helper function based
  on a SE answer
- Check for empty directories, because the hinder getting a file name...
Remove redundant output, improve logging and display

Around line 200 we can now set `autoclose` meaning the script runs
through *all* the folders, looks at the images, saves the plot and
continues itself.