horizontal / vertical splits

In the tiled rendering case the horizontal / vertical splits were
not implemented, so the leftmost visible column is 0.
So preserve horizontal / vertical splits when saving the document

Change-Id: I15b6f009910e51fdaf475de5aac1ebded16c1956
Reviewed-on: https://gerrit.libreoffice.org/69926
Tested-by: Jenkins
Reviewed-by: Henry Castro <hcastro@collabora.com>