Parametric (curve/LUT) parameters: ParamValue::Parametric holds one
ordered control-point curve per dimension (identity default over the
declared range), evaluated as piecewise cubic Hermite with auto
(centered-difference) slopes; the full suite — evaluate / count / get /
set / add / delete / delete-all — with the spec's error codes, descriptor
defaults copied to instances, and instanceChanged notifications on
edits. paramDefine accepts OfxParamTypeParametric; the dimension/range
and UI-colour properties round-trip. 148/148 real plugins discovered,
135 registered (one more than before: the parametric-suite consumer).