- some paraview versions (eg, on windows) don't support float, only double.
This mostly affected the vtkSurfaceWriter.
The foamToVTK is also affected, but since it also supports the XML
output formats (vtp, vtu) these can be used instead.
- this shifts responsibility away from caller to the individual writers
for knowing which file formats are supported and which file ending is
appropriate. When the writer receives the output format request,
it can elect to downgrade or otherwise adjust it to what it can
actually manage (eg, legacy vs xml vs xml-append).
But currently still just with legacy format backends.
