Indent
TODOs
xxf:case: fix return type
Implement #1089 "XForms 2.0 caseref support"

- static switch/case controls
- switch
  - evaluates caseref binding
  - reads caseref binding to update selected case upon refresh
  - writes caseref binding upon toggle
- tests

What's not implemented yet:

- dispatch of xforms-binding-error
- dispatch of xforms-select/xforms-deselect