* Adds antag subsystem to handle antag datum init. Moves antag datum defines to a module. Antagging new_players via traitor panel moves their created bodies to appropriate spawnpoints.
* Un-oopsies some unnecessary init order changes
``/mob/dead/observer`` -> ``/mob/observer/dead``
``/mob/eye`` -> ``/mob/observer/eye``
Reason being that they are similar in that they both don't interact with
the world in any way. Some procs were shared, some checks as well, and
it overall makes more sense this way. Plus, there were no ``/mob/dead``
mobs.
