All the entities' base class.
KKoishi_
the health of the entity.
The universally unique identifier(UUID) of this object
What to do after hit.
Test if the object collide with another object o.
Actions invoked after the entity is dead.
If the entity is dead.
How the entity move.
Render the object.
The shape of the entity, used for collide test.
Check the state of the object, and if this need to be removed, true should be returned.