Accurate entity hitboxes

[rj00a]

entity.rs has a function called hitbox which, as you can guess, returns the Axis-aligned bounding box of an entity.

Extracting correct hitbox data automatically appears to be infeasible because it depends on the entity's state and varies wildly between different entity types. This info will have to be filled in manually.

Right now there is a bunch of placeholder data and some todo!s.