Torus construction (CreateCanonical/MakeNurb), operator==, Copy, offset,
STEP/NURB conversions, STEP evaluation, iso circles,
RebuildSTEPFromNURBParameters, Transform and ReadFromDB (the last two end
in the unported SmSurfOfRevolution part). SurfOfRevolution's NURB and
polar-converter rebuilds take the iso-curve maker so the torus override is
used, as upstream's virtual call. Surface::read_from_db reads the torus
record before the unported base record.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Andreas