o Minor bugfixes (circuitpadding):
    - Add the abilility to keep circuit padding machines if they match a set
      of circuit state or purposes. This allows us to have machines that start
      up under some conditions but don't shut down under others. We now
      use this mask to avoid starting up introduction circuit padding
      again after the machines have already completed. Fixes bug 32040;
      bugfix on 0.4.1.1-alpha.