- it is a well-known and often feed-backed missing feature that SectionCuttings fails for intersecting objects.
To resolve this, the objects must be put int a BooleanFragments object.
- this PR adds this functionality as option.
- since a BooleanFragments objects has a specific color, the different colors of the objects cannot be preserved. Because of this disadvantage, the BooleanFragments option will not be the default.
- this PR also modernize all for loops
* [Part] feature to make persistent section cut views
* one aim is to have a feature to make real cuts, not hollow ones like with clipping
* the second one is to have a persistent view, so an object in the tree that can be further exported, meshed etc.
For a detailed description with examples see https://forum.freecadweb.org/viewtopic.php?f=17&t=52441