Damaged by terrain

This is a trait that replaces the PoisonedByTiberium trait for a more general approach, this now not only works on resources but also on terrain, have a unit that cant live on anything but tiberium add Clear and Beach to the Terrain variable (you might need to add Rough too but I have no idea what terrain that is).
I'm just going to guess that when this was written there was no `TiberiumHeal` yet, and when that was added this was missed and never updated. I say we make this use `TiberiumHeal` as well.