Drone thingsssssssss

Adds hat and mask slot, so they can be adorrrrrrrrrable
Ports internal storage system to already existing slot system
New default_storage and default_hatmask vars which allow future child classes of drones to have default items easier
Adds drone_type var to drone shells for the same reason

Fixed a bug where cannibalized drones would gib
Moved drone hud code to its own file

Adds Syndrome, a modified maintenance drone tasked with destruction of the station (KEEPER version of antimov)