[Dev-luatex] Wrong placement of image nodes in non left-right directions

The image node placement code doesn't doesn't handle directional changes, which results in wrong placement of images in right-left (and other) directions, see the attached simple test suit (all images should fit into the frames). This patch attempts to fix this, but it does handle _LT/_LB and _RT/_RB only, as I can't test the others in PDF mode. Regards, -- Khaled