inspect.compare: where two versions of a part differ, without a boolean of the two (#1423)

New command inspect.compare {a, b, tolerance?}: measures of both and their differences, two-way surface deviation from a bounding-volume tree, regions beyond the tolerance clustered by side (only_in_a / only_in_b) with integrated volumes and faces, a verdict, optional face colouring as one undo step, and warnings for open meshes. Geometry in solidcraft-geom (compare.rs), command in the engine. Closes #1363.

crates/geom/src/lib.rs

@@ -11,6 +11,7 @@
 mod arcfit;
 pub mod brep;
 pub mod bspline;
+pub mod compare;
 pub mod env;
 pub mod fill;
 mod mesh;