Fixes Solid infill where there should be none #6482
Also the safety offsetting was revised to be enabled only where needed,
the "do safety offset" is now easy to discover by
a new ApplySafetyOffset::Yes enum, and safety offset over union, which
is better done by offset() / offset_ex() has been replaced with
new union_safety_offset() / union_safety_offset_ex() functions, which
better convey their meaning and which could be better optimized than
union() with the safety offset applied.
this moves the print_time directly after the input_filename_base,
so it has the most chance of surviving truncation by marlin.
temperature is also added in front of the filament_type.
which was broken with 68666de521b1cb15e41ac6728c0e8d3b4b0d4ed0
"Reworked the "new" bridging to respect the bridge_flow_ratio
by maintaining extrusion spacing, but modifying the extrusion width
and / or height."
from the background slicing thread, that supports cancellation.
The generic mechanism is used for generating thumbnails into G-code and
Fixes Fix deadlock when canceling the slicing while gcode is creating thumbnails #6476
Thanks @supermerill for pointing out the issue.
Steps to repro:
1. Add 2 objects, add Settings for some of object -> Object Settings item is selected
2. In the 3D-scene select another object -> BUG: no changes in the ObjectList
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.
