Spinning things on L7
one-way wall L9
Improve explosions

Change wait delay on levels with bg animations?
Have 20 lemmings on some levels?
Only scan for Maximum Lemming number rather than maximum possible number?


+ have bridge stop building when hits wall
	(real game, reverses too maybe?)
+ wait a second after last lemming gone to exit
+ fill in some of the ground so we don't get stuck when digging
+ See if the jerky animation is due to starting at an odd x vs
	even x, maybe we should start animation 4 frames in if that's
	the case.  Or maybe it's the shift for odd frames, make
	the shift the other way if walking left/right
+ Make particles thicker?  Look fine, not show up in recordings
+ Erase particles as last step

+ offset the frames when nuking so not simultaneous
+ on explosion, start with invisible 6 so we always get a full 5s