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/engine/src/cmd/mod.rs

@@ -22,6 +22,7 @@ macro_rules! planned {
 
 mod browser;
 mod clipboard;
+mod compare;
 mod component;
 mod component_clone;
 mod component_clone_assembly;
@@ -256,6 +257,7 @@ pub fn command_specs() -> Vec<&'static CommandSpec> {
     v.extend(file::COMMANDS.iter());
     v.extend(metadata::COMMANDS.iter());
     v.extend(inspect::COMMANDS.iter());
+    v.extend(compare::COMMANDS.iter());
     v.extend(materials::COMMANDS.iter());
     v.extend(material_properties::COMMANDS.iter());
     v.extend(libraries::COMMANDS.iter());