Pathbar:  Altered shape to wedge, improve styling
Tweak spacing between breadcrumbs
pathbar: Make DnD highlighting a bit more consistent with the standard
GTK highlight.  Calculate button X position better so spacing is better
across themes.
pathbar: Improve directory name spacing in the breadcrumbs chain,
reshape arrow a bit.
Make pathbar a bit narrower, pointier.  Play with style a little bit.