[entity] continue cleanup of Entity/AnyEntity namespace
* prefix by cw_ or _cw all '2nd zone' attributes / methods, other
most commonly used will be done later (some methods used by client
are made private anyway when they are for internal purpose anyway)
* kill set_eid, use direct affectation instead
* kill the auto-transmutation feature (pre_add_hook), hence releasing
3.9 will require releasing file cube as well