AI rework

PlayerCtrldComp and AIComp now both inherit from Character class, which
defines functions (previously defined in AIComp) both types of character
will eventually need to interact with the world.
SightComp and SeeableComp now both inherit from SightFaction, which
defines how characters react to visible objects (still rough
implementataion). The Blackboard class now sorts some visible objects
appropriately (not enemy characters; eventually, determining how a
character reacts to other objects/characters should be delegated to
another class).