Ideally, you could keep the health modifier in the pool structure so you
dont need to calculate the inverse every time again, but since the 3rd
spot meant stuff for bosses and it was used in other places, i didn't
want to mess with it.
Ideally this event would not be triggered since it won't change
anything, but it seems big waves of biters trigger it with 0 damage, so
might be better to ignore those
Fused boss units into biter_health_booster.
Unit evasion replaced with custom unit health pool.
Boss Units no longer update their healthbar infinitely fast.
Map Intro moved into the main panel.
some globals to locals
