This patch makes multi selected chapter promote demote results the same
as when each selection is promoted or demoted individualy. Multi
selected chapter promotions (moved up) are done in tree list order from
top to bottom. Multi select chapter demotions (moved down) are done in
tree list order from bottom to top.

Change-Id: Iee238fd2bc84521a6eacf6688b94fa0be1e32f67
Reviewed-on: https://gerrit.libreoffice.org/71270
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>