IfcRelConnectsElements elements type

In IFC4.3 some relationships have been broadened for example IfcRelReferencedInSpatialStructure:

* attribute RelatedElements type, Changed from "set[1:?] of [IfcProduct](https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcProduct.htm)" to "set[1:?] of [IfcSpatialReferenceSelect](https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcSpatialReferenceSelect.htm)"

https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcRelReferencedInSpatialStructure.htm

The question is whether IfcRelConnectsElements is still appropriate to only include IfcElement and not things like IfcLinearElement IfcPositioningElement IfcSpatialElement, or even things like IfcAnnotation.

Start with the IFC4.3 definitions for IfcRelReferencedInSpatialStructure and IfcRelConnectsElements, then compare the referenced select or entity types with the listed element classes. Done means reaching and recording a decision on whether IfcRelConnectsElements should broaden its allowed type, with the specification updated if maintainers agree.

Written by the indexing model from the issue text.