Release v4.18.0

An Object property can now describe its own fields, so a host can edit a structured value with a nested form instead of a raw JSON box.

Added

• PropertyDescriptor.properties describes the fields of an Object property. A field's path is a single name relative to the object and a field may itself be an Object or a Collection, so a structured value of any depth is describable. See Descriptors. (part of #70)

Changed

• validateValue checks an Object value that has properties field by field: it must be a record, every described field must fit its descriptor, required fields must be present and a field the descriptor does not describe is refused. An Object without properties still accepts any record or array. (part of #70)
• validatePackageBundle checks nested descriptors - duplicate fields, collections without item descriptors and enums without choices - at every depth, including inside collection items. (part of #70)
• Icon diagnostics also check icon fields inside a described Object value. (part of #70)