The invulnerability had solely been used for the cheering / promotion state before
until it was used in survival of the fittest for the treasure seeking woman.
Since D215 is now available,
we can use a special filter template that makes units undeletable and invulnerable
without adding one template for each unit template that should have these properties
instead of setting the invulnerability at runtime from the simulation,
thus allowing the AI to recognize the invulnerability and adapting to it.
The new template property should also be used for the relics in D152,
so that the AI doesn't attempt to destroy the entities.