Make E2 Object-Oriented (Internal)

[Denneisk]

Thought there was a suggestion for this but it was for user-defined types. This is referring to how E2 handles types internally.

Namely, inheritance and polymorphism. This would open the door to make E2 a lot easier to extend, and also help E2 code be self-documenting by reducing usage of "omniclass" E2 types; for example, a new npc, player, weapon, and holo type could all extend entity; table could extend array or share a superclass that guarantees shared functionality.