Make use of upstream's correction for correctness

  - Multimer buffer now introduced the expiry field, which is used to
    mark the fencepost issue of when fuel is deducted as per the
    stateTimestamp.  This is now corrected, as stateTimestamp is the
    final timestamp where the fuel value reported is accurate.
Basing remaining calculations on the expiry.

  - As all resource (fuel) calculations are done relative to the expiry
    timestamp which is also the stateTimestamp, various assumptions had
    to be corrected.
  - However, now the concern is reversed - API returning states from the
    past can no longer considered as out of date.  This however works as
    the reinforced towers will assume fuel consumption once they exit
    reinforcement.
  - Fenceposts are hard.