UI to let the user visually set split points

[torakiki]

From the website:
A visual preview of PDFs being merged or split would be great. It would avoid separately opening PDF files whenever I need to reference them to accurately split the files.

The PDF preview, combined with a more visual way to add break points where splits would occur, would be ideal. This way i know exactly where the PDF will be split all within the interface. This would make it much easier to use and much more user-friendly.

Thanks!

[torakiki]

This is going to be created as a module of PDFsam Visual (or whatever name we'll decide for it)