effectcraft-project writes and checks the envelope of .ecproj files with
craft-ecproj-format from craft-libs: File (savedBy, then the saved view
and the project) with to_json and to_json_compact for Save Compact
Project Files, check_schema and its message, SCHEMA_VERSION and
saved_by, which stay re-exported under their names. Project, SavedView
and the schema 1 conversion stay here.
Saved files are byte-identical. saved_by now reads only a JSON object,
so a project written as a JSON array no longer reports a savedBy.
dotCooCoo