sw: rework RTF export of text frames

Export these as new-style frames. Not counting future possibilities,
this commit finally fixes the following problems:

- borders: spacing to contents wasn't exported at all
- wrap: top/bottom and left/right spacing exported even in case they do
  not equal

Change-Id: I058e00e677e20bc9501b8de320f941f256e8b6f1

sw/source/filter/ww8/rtfattributeoutput.hxx

@@ -552,6 +552,11 @@ private:
 
     unsigned int m_nPostitFieldsMaxId;
 
+    /// Set by FormatFrameSize(), read by Format*Orientation().
+    const SwFmtFrmSize* m_pFmtFrmSize;
+
+    std::vector< std::pair<OString, OString> > m_aFlyProperties;
+
 public:
     RtfAttributeOutput( RtfExport &rExport );