shadows, scorch marks and blood
fix some collision logic, start adding structures
fix stats
grenade physics, better collision logic

grenades (or rather, thrown items) can bounce off agents and structures
(stunning the former)

agents now do a better job of going around structures to reach their
target
first stab at motorhome, crosshair pointer

need to fix stacking issues, as well as rebound tangents and height

don't offset pointer above player, render it as a crosshair on the ground
when the player is tracking it

fix grenade crash