Class-A surfacing 3/3: blend curves, curved-edge fillets, the G2 corner and continuity analysis (#1642)

Thanks @midasdf.

crates/geom/src/lib.rs

@@ -9,6 +9,7 @@
 #![forbid(unsafe_code)]
 
 mod arcfit;
+pub mod blend;
 pub mod brep;
 pub mod bspline;
 pub mod compare;
@@ -23,9 +24,10 @@ pub mod tspline;
 mod vec;
 
 pub use arcfit::MAX_FIT_PIECES;
+pub use blend::hermite_bezier;
 pub use mesh::{Aabb3, BoxedTriangle, InsideIndex, MassProperties, Mesh, MeshMeasure, find_close_pair};
 pub use plane::Plane;
-pub use profile::{Loop2, MAX_BEZIER_DEGREE, Region2, Seg2, bezier, regions_apart};
+pub use profile::{Loop2, MAX_BEZIER_CTRL, MAX_BEZIER_DEGREE, MAX_DERIVATIVE_ORDER, Region2, Seg2, bezier, regions_apart};
 pub use vec::{Vec2, Vec3};
 
 /// Geometric tolerance for coincidence tests (mm).