1) Removed the already commented-out scaling / unscaling when doing
"safe offsetting"
2) Removed some of the "safe offsetting" at calls where it never was used.
3) Reworked Clipper & ClipperUtils to pass Polygons / ExPolygons / Surfaces
as input parameters without conversion to ClipperLib::Paths. This
should save a lot of memory allocation and copying.
4) Reworked conversions from ClipperLib::Paths & PolyTree to Polygons /
ExPolygons to use the move operator to avoid many unnecessary allocations.
5) Reworked some "union with safe ofsetting" to "offset_ex", which should
be cheaper.
Relies to:
Concentric Fill Start Point - New Feature Request #4948
Feature Request: Archimedean Chords - Option to define direction of travel (Inside-Out or Outside-In) #5214
Fixed some issues in internal anchors of the Adaptive Cubic infill.
The ugly and dangerous implicit casting operators in Line, MultiPoint,
Polyline and Polygon were made explicit.
