Resolves: fdo#86466 Wrong background color shown in format table in impress

regression from

commit 440e2031ce8cffc8dc573e359a330236f9c11dfb
    bnc#882627: Allow to edit spacing to contents even with no borders visible.

which was an attempt to fix regression from

commit 9e5342509b302ba1f816f21cc3ad1cb7093982e0
Date:   Mon Jun 3 14:22:07 2013 +0200

    copy values from the original item set

    ... because SfxAbstractDialog::GetOutputItemSet() only contains the
    items that have been _changed_ in the dialog.

Now format color shows the expected color, and loading the sample for
bnc#882627 and selecting cells and changing the border distance (etc) doesn't
cause bulleting and paragraph alignment properties to be stripped away

Change-Id: Id414e09faa221d151f393971654b17bbe9f46d81