Changed, Things mode, cosmetic: tweaked thing sprite/bounding box appearance a bit more...
Fixed, Linedefs mode, cosmetic: fixed event lines and sector highlights flickering when view panning was started while displaying action highlight.
Changed, Things mode: things are now rendered with a bit of transparency, so things beneath other things are now visible.
Fixed, Things mode: in some cases it was impossible to highlight a thing beneath other thing when their positions were the same.
Changed, 2D modes: changed thing bounding box and arrow image.
Fixed, cosmetic, 2D modes: in some cases thing arrows were rendered bigger than thing bounding boxes.
