Changed currentNAVObjective->Target nomenclature.
Created NAVTargetableBehavior
NAVSystem notifies NAVTargetableBehavior of objects being targeted.
Created CustomDeathBehavior
Created ChangesBehaviorWhenTargeted
Boss starts out as invincible.
Added Boss/Tunnel NAVObjective interaction.
Added support for hidden tunnel entrances and exits.
Bugfix: Disabled DamageableBehavior is still damageable.
Created blue plus and minus radar artwork.