one plate assayed, and the refill that only two of them need
============================================================

one job: 2 units needed, 2 in stock
-----------------------------------
    0 ->   3  morning    processing     make_plate
    3 ->   5  morning    transport      transport
    5 ->  15  morning    processing     assay
   15 ->  17  morning    transport      transport
   17 ->  18  morning    processing     discard
  makespan 18, 0 replenishment(s)

two jobs: 4 units needed, 2 in stock
------------------------------------
    0 ->   3  morning    processing     make_plate
    0 ->   4             replenishment  reader
    4 ->   6  morning    transport      transport
    6 ->   9  afternoon  processing     make_plate
    6 ->  16  morning    processing     assay
   16 ->  18  morning    transport      transport
   18 ->  19  morning    processing     discard
   18 ->  20  afternoon  transport      transport
   20 ->  30  afternoon  processing     assay
   30 ->  32  afternoon  transport      transport
   32 ->  33  afternoon  processing     discard
  makespan 33, 1 replenishment(s)
