I've added edge shading to the latest build, 298 (click here to play). It's not perfect yet, but it's actually quite handy for seeing which items are on which height levels. I also made a small optimization to lighting to help render somewhat faster, although there are additional optimizations to speed this along.
Here's a screenshot with edge shading and lighting turned on:
And here's the same area without it:
Great! just adds that extra bit :-)
Looks awesome with it! Awesome job.
Thanks :D