Current problem.
- AST doesn't seem to be rebuilt, so we end up having stale references.
Who's supposed to trigger the AST reconstruction?
-> Added ChangeVisitorImpl and that fixed it.
- Ctrl+W doesn't work on attributes.
presumably SelectWordUtil.registerSelectioner(...);
Defining intermediate PSIs (like JellyAttribute) made it work
- Auto-completion needs to work
- xmlns decls are marked as errors