Struct as subclass of <mutable-explicit-key-collection>.  Compiles without error, but not yet tested.
Fixed bugs in element(<struct>, <string>)
Merge @file references against the parser's filename, if any.  Not quite right...left TODO comment.
Bug fix + slight improvements to priting.
Remove test-ordered-table-fip.
Remove unsupported =..x syntax.
Add TODO comment.
Add test-forward-iteration-protocol