Option to disable image extraction/merging

[jerbob92]

I'm playing around with the library, and having some pretty nice results with it! However, in my tests it often recognizes large pieces as an image, and then doesn't return the text and/or tables within that image (probably because it merges it into the biggest found layout item that is detected).

I think it would be a nice option to be able to disable the image extraction/merging.