Removing the legacy FrozenActor to Actor workaround
fixes a number of long-standing bugs.
This also prevents units from losing their target when
it transforms into a different actor type.
Note: Projectiles that can track their target need minor additional changes, but for InstantHit (which already implemented support for this) and unguided projectiles (Bullet, GravityBomb) this commit is already sufficient.
Enabled firing multiple armaments at a target simultaneously.
Each armament defines own cursor for targeting.
The force attack modifier influences armament choice for target.
Autotargeting modified to handle firing multiple armaments simultaneously.
As a consequence, healers (medics) no longer require separate Heal
activity and AttackMedic and AutoHeal traits.
