Fix #1417 (airlocks and emags)
Created by: wild-billy
Added a busy check so emagged airlocks can't be crowbarred apart a bajillion times during the do_after()
.
Also fixed emag behavior (now properly forces the airlock open).
Also fixed a null.len
runtime related to access on the electronics.
Fixes #1417 (closed) (airlocks breaking when emagged)
This is a band-aid fix. Door-related code is terrible and needs refactoring.