Combat AI

Extended character AI to properly accomodate combat. AI characters can
now attack opponents until their health reaches 0 and no more enemies
remain, when they exit combat.

Also modified AIManager classes to remove AIComps, SeeableComps and
SightComps without deleting them or losing their references (since the
managers are responsible for deletion eventually), only preventing them
from being updated again.

When the Sinbad character dies he bursts into dance, for want of a
better animation...