Add Order.ExtraData field.
Add ITargetableInfo interface for querying target types.
Change WeaponInfo.EffectivenessAgainst to take ActorInfo.
Replace Target.IsActor and IsValid with Target.Type.
Merge IOrderTargeter.CanTargetActor and CanTargetLocation.
Allow world and (render-) player actors to render.
Track per-player frozen actors.
Show tooltips for frozen actors.
Allow frozen actors to be flashed.
Add FrozenActor target type.
Implement attack orders against frozen actors.