Cleanup: Removed unused and misnamed or miscalculated variable

* Removed all references to unused variable totalCO2MolesConsumed, as
  it is either misnamed or miscalculated.  (Moles per square meter as
  calculated, and without waterFraction.)

* Left totalCO2GramsConsumed, which is correctly calculated from
  myMolesOfCO2Inhaled.

* Parallel to O2: we have totalO2GramsProduced but no
  totalO2GramsProduced.