[Enhancement] Detect and fix folds

[nicolas-raoul]

When a paper has been folded in two or four, it can be hard to make it flat. That results in non-rectangle shapes, that could maybe be detected and corrected? Very low priority.

[allgood]

I think that the detection is very hard, because instead of searching for object of 4 points it will need to look for 4, 5, 6 7, 8 (to detect a four part folded document - and yet will be impossible to determine the center). but, I am wanting to build a manual crop screen for documents that couldn't be detected, this screen can easily have 9 dots (8 border + center) that can be moved. Then the currently 4 point should be repeated for each section.