v2.5 update

Fixed napalm destroying bedrock and then endlessly looping from top of
the world to the void.
Fixed rotation of wood.
Fixed placement of special objects on airships (besides doors)
Added move command, /ac move.
Added new option when ships are above a certain size they will only
render glass blocks under the passenger's feet until they have stopped
when they will render the whole ship again. Defaults to 1000 blocks.
Signs should now keep their text written on them.