Use global coordinates when computing tabs

[sapphire-arches]

This makes the computation of tabs take place in global coordinate space, so things don't break in weird ways when working with shapes from different bodies/parts. This probably needs additional testing/refinement before being merged.

[execuc]

Hello, Thank you for your work ! Have you got any simple .FCStd file which lead to an error without your fix ?

[luzpaz]

@bobtwinkles please follow up

[hstarmans]

To summarize; it doesn't work, but contains some steps in the right direction. @bobtwinkles changes do partly solve the issues. If I click preview, the parts are positioned correctly but screw holes are still positioned incorrectly, tested on freecad 0.19, see image. I expected this image. I solved the problem by using create a clone in part design.