Improve print preview and printing with high DPI

All print related scaling is based on 96DPI, so always let the printing contexts return this,
and also adjust the font to this DPI.

include/wx/msw/dcprint.h

@@ -36,6 +36,13 @@ public:
 
     virtual wxRect GetPaperRect() const wxOVERRIDE;
 
+    virtual wxSize FromDIP(const wxSize& sz) const wxOVERRIDE
+    {
+        return sz;
+    }
+
+    void SetFont(const wxFont& font) wxOVERRIDE;
+
 protected:
     virtual void DoDrawBitmap(const wxBitmap &bmp, wxCoord x, wxCoord y,
                               bool useMask = false) wxOVERRIDE;