there may have been changes not caught by undo to the object's
ordinal, so on use of RemoveObject (or ReplaceObject) call GetOrdNum
on the object to get its current position within its parent.

We can keep nOrdNum for the desired dest position within the parent
for InsertObject

Change-Id: I3bdabf387dd630fc1fadaaa1f3d8c05e93865e4f
Reviewed-on: https://gerrit.libreoffice.org/70409Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
Tested-by: Jenkins