text: Title: Make plot_duplicates output clearer
  Body: ## WHAT
  Make `plot_duplicates` output clearer.
  
  ## WHY
  The graph plotted by `plot_duplicates` output can be cluttered, especially when there are several duplicates found for an image. The titles of each image run into each other, which makes it hard to read the plot. Additionally, the titles can be hard to read, possibly due to a static dpi. An example can be seen below:
  
  ![imgdedup_plot_issue](https://user-images.githubusercontent.com/9531254/101158741-86070500-362c-11eb-87ed-eb5337cc00ac.png)
  
  
  ## HOW
  In the current implementation, a fixed number of columns in the layout is used (= 4), the top row is reserved for plotting only the original image and the number of rows are dynamic. There are several ways to remodel this:
  - Make the number columns also dynamic so that image titles do not run into each other.
  - Process the text output so that it is legible.
  - Come up with a completely new layout.
  