implement UNFOLDING SEQUENCE for sheet metal parts

[matteo_pallaroni]

Some parts, altough created correctly with sheet metal features, cannot be unfolded due to a lack in the algorhytm

the flat pattern looks like this

very helpful for parts created with progressive dies

[mrattray]

I'll add that the ability to unfold parts with "double curvature" (plastic deformation in multiple directions) would be great.

[matteo_pallaroni]

Absolutely; it will be great for spheric/emispheric shapes and helical deformation. wonderful