Mob persistance working correctly

-Mobs now persist in a manner similar to objects across server sessions.
  However, each mob in the world is saved as a unique instance, so
health, inventory, exp, etc are all retained between server sessions
-Fixed bug with duplicating mobs between server sessions
-Fixed bug with duplicating mob inventories between sessions
-Fixed bug where random items in the prototype mobs' inventories were
showing up in player inventories.
-At this point, mobs don't do much, except display, save, and load.
Next up, a mob spawner object component, which gives different manners
of generating mobs in a room.