i.e. paint to VirtualDevice as well, not only to Window.
Removed the no longer needed switch between buffered and unbuffered overlay,
this removes the flickering white block.

(cherry picked from commit 5ab32faf)

Conflicts:
	editeng/inc/editeng/outliner.hxx
	editeng/source/editeng/impedit.hxx
	editeng/source/editeng/impedit3.cxx
	editeng/source/editeng/impedit4.cxx
	svx/inc/svx/sdr/overlay/overlaymanager.hxx
	svx/inc/svx/sdr/overlay/overlaymanagerbuffered.hxx
	svx/inc/svx/sdrpaintwindow.hxx
	svx/inc/svx/svdpagv.hxx
	svx/source/sdr/overlay/overlaymanager.cxx
	svx/source/svdraw/sdrpaintwindow.cxx
	svx/source/svdraw/svdedxv.cxx
	svx/source/svdraw/svdpagv.cxx

Change-Id: Ibf4fcba77b120187fbae2454d136d2acd74be119