All changes are about not assuming logical top is a lower y value than
logical bottom, by going via the SwRectFnSet abstraction, which already
does the right thing.

Change-Id: I94a9881b018ad14b02e97425f60af01aa3fd9269
Reviewed-on: https://gerrit.libreoffice.org/69226
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>