[PR] Airlock packet protection, take two

[pali6]

Alternative idea: have the access code be binary, something like 10101010 and depending on how important the door is you might have some of the binary digits obscured so you'd see 1010*10*1* on the armory door for example.
I'd like some way of making different tiers of security like this.

EDIT: Nevermind, that'd prevent mechcomp hacking compeletely and I don't like that. Maybe important doors not providing *exact* number but just an estimate?