creature.combat: Fix missing call to UpdateDamageImmunity
rules.dmgred: Remove obsolete function.

- Add Rdd innate damage immunity.
- Reorder parameters of SetBaseDamageImmunityOverride
Add rules.damage.
object.combat: Add debug damage immunities

- Add damage names to debug prints.
object.combat: Fix DebugDamageImmunities... Oops.
Add rules.immunities for determining/setting innate immunities.