v1.6.1

Version 1.6.1

• Various bug fixes
• New mesh-quality controls: segment/facet encroachment angles
  (-q//#, -q///#), minimum edge length (-L#) and element growth
  ratio (-L/#) constraints, and a new multi-phase mesh-improvement
  pipeline (flip, edge collapse, Steiner insertion, smoothing).
• Flip operations now honor angle validity constraints
  (flip_valid_angles), avoiding near-degenerate elements during
  boundary recovery and Delaunay recovery.
• New options:
  • -A2 (treat interior subdomains as holes)
  • -rS (use volume size map during refinement)
  • -g2 (Nastran .nas mesh output)
  • -NS (annotate .node output with Steiner point tags),
  • -K (prevent mesh coarsening during refinement)
  • -G (suppress writing metrics to output)
• New .region input file support (tetgenio::load_region,
  Subdomain_Facets) for defining subdomain boundary facets and holes.
• Faster in-sphere predicate via pre-calculated sub-determinants
  (pre_calculate_insphere/insphere_use_subdets), still falling
  back to exact arithmetic when needed.
• Removed the legacy NEU_MESH format and the -H hole-mesh option.
• Modernized CMake build: project versioning, proper install/export
  rules and package config (find_package(TetGen))
• Optional CTest-based test suite with more than 300 test cases
• Upstream repository on codeberg.org with read-only error on github
• New contributing guidelines (dual AGPLv3/MIT licensing for contributions)