- ModelToViewHelper: add new flag REPLACEMODE, which causes fields and
  footnotes to be replaced with ZWSP instead of expanding them
- SwXFlatParagraph: add FootnotePositions and FieldPositions properties
- GrammarCheckingIterator: invoke XProofreader::doProofreading with
  properties FootnotePositions and FieldPositions

Change-Id: I9b66a37aac94f940546e812d8b85a35aebd8181a