Implement Reference and Expand relations

[wackywendell]

Summary

Implement support for Reference and Expand relations in both parser and textifier.

Problem

Reference and Expand relations are not currently supported in the text format.

See ReferenceRel and ExpandRel for the relation definitions.

Goal

Add support for ReferenceRel and ExpandRel operations.

Success Criteria

• Parser supports reference and expand relation syntax
• Textifier handles reference and expand relations
• Proper handling of relation references and expansions
• Roundtrip testing works