A3t

- Filter expressions are parenthesized.
A3t

- Implemented the stubbed outline of ::findMissingOperators, for injecting
  'and' or 'or' into filter expressions, where needed.
A3t

- Removed tag 'EXPANDED', which can be replaced by a call to node.size ().
A3t

- ::findAttribute now properly inserts sub nodes.
A3t

- ::findMissingOperators now detects all locations where a logicl operator
  is needed.
A3t

- Switch sub nodes from using 'value' to the more uniform 'raw'.