One big paragraph spacing control was splitted
to separated widgets. It will be possible to
reuse that in the sidebar. Also layout is better
because explicit size setting is no longer needed.

Change-Id: Ieb200af4a9a6120ae03b22b27da56256aa816193
Reviewed-on: https://gerrit.libreoffice.org/35801Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>