laying groundwork for animated transitions
Merge branch 'master' into animation
simple looping animation working.

my example resembles a pulsating metroid turning into a bird and back.
definitely could use some tweaks, and it's a bit stuttery.
improved performance of index-of
more performance tweaks.

getting some interesting benchmarking results.
armed with those, took another chunk out of the creature computation
time via improving turn-direction.
randomize button for animations
minor cleanups
more cleanup
use depth instead of depth-remain; more code cleanup.
gradual animation kinda works
move prod cljsbuild to :prod profile