- Separate the 3 bands -- dangling, sloping and full overhanging -- regions and handle them with different support force deficits.
- Use a heuristic for overhanging edges to increase the number of support points generated for them
- Try to make overhangs and slopes deficit depend on stable area.
- removed define USE_AABB_INDIRECT (which switched between old and new AABB implementation)
- removed define SLIC3R_SLA_NEEDS_WINDTREE (relied on igl and was not used anyway)
- new define SLIC3R_HOLE_RAYCASTER (hides currently unused code)
- slight include cleanup
- removed obsolete source file SupportTreeIGL.cpp
