There were also two cases here:

- changing the selection with the keyboard or single-click only updated
  the selection in the navigator
- pressing enter or double-click also selected the shape in the main
  window and gave the focus away

Introduce a 3rd case for single-click: update the shape selection but
doesn't give the focus away. This way double-click is not needed to sync
navigator -> main doc selection but keyboard navigation should still
work.

An additional trick is to make sure that the current shell is the draw
shell (and not the slide sorter) after navigation, so follow-up
operations work with the selected object and not with the whole slide.

Finally, a third related problem was that the selection jumped back to
the item of the slide after clicking on a shape in the navigator. The
reason for this was the navigator list was constantly cleared and
re-filled in SdNavigatorWin::InitTreeLB(), as
SdPageObjsTLB::IsEqualToDoc() returned false (even if the list was up to
date) in case of shapes which had children but no name. Fix this by
using the same SdrIterMode::Flat iteration mode that
SdPageObjsTLB::AddShapeList() does, so the fill and the equality check
of the navigator iterates the same way.

Change-Id: I0bfc3e8b49f7ef01d5797a68284616dcd2a81c5d
Reviewed-on: https://gerrit.libreoffice.org/50118Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>