Currently when printing via SwXTextDocument::getRendererCount()
two STL containers in class SwRenderData are filled with bare pointers
to page frames from the layout.
These pointers are then used by SwXTextDocument::render(), which takes
one page out of the map and prints it via this non-ref-counted pointer.
This bizarre design will not be tolerated; instead, when printing a page,
iterate over SwRootFrm::GetLower() until the requested page is found.
This is slower, i.e. O(n^2), but at least it does not crash.