Design properties: project, author and licence in the design, its exports and inspect_design (#1015) (#1189)

A design carries metadata (format 21): project, part number, revision, author, organization, description and license, plus other tools' data under reverse-DNS keys, kept as written. Edited in the Design Properties window (Document Settings), set by document.metadata.set, reported by inspect_design, and written into STEP, IGES and 3MF where the format has a place for them. Translated, with tests.

crates/doc/src/lib.rs

@@ -28,6 +28,8 @@ mod history_names;
 pub use format_offsets::whole_profile_selection_from_value;
 pub mod joints;
 mod lineage;
+pub mod metadata;
+pub use metadata::Metadata;
 pub mod motion;
 mod name_lookup;
 pub mod naming;