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).
A `SafeTerrain` field might make sense though so why not just keep it. We have several traits that allow both black- and whitelists which is useful to write cleaner mod rules.