This allows rendering of a vertex directly, rather than just as an
edge endpoint. They're currently drawn as small '+' signs. A
round dot would be better, but the code is passing a list of line
segments around, so this is simpler.
Visualization animations are now exported as animated GIFs. The
Windows stuff is a bit lame so I threw together some code that
stitches a bunch of GIFs together.
The GIF doesn't quite match the preview, because the preview scales
the individual frames, while the animated GIF uses the largest frame
as the size and is then scaled based on that. Animating frames of
differing sizes together is bound to be trouble anyway, so I'm not
sure how much to fret over this.
