Fixed some old support and infill issues.
Fixes support problem #4295
Fixes Parts of interface layer extends beyond supports and cannot be printed
Fixes support missing under horizontal overhang #6058
Fixes Slicer double-traces small sections of Rectilinear Supports, causes
Fixes plastic buildup and nozzle crashes #4951
Fixes Add "Angle Interface layers" #2969
1) New algorithm for connecting along the perimeters is now applied
to Honeycomb, Hilbert and similar planar filling curves.
2) The old expensive path chaining is not applied if the new algorithm
to connect along the perimeter lines is called afterwards.
by @supermerill and @wavexx
WIP: The function Fill::connect_infill() is being rewritten
to utilize spatial structures wherever possible for lower CPU load
and less dynamic memory allocation.
for islands with another islands in their holes.
Improvement of chaining of infill lines for 3D honeycomb, Gyroid and
Honeycomb infill: New TSP chaining algorithm is used.
