CHANGES IN VERSION 1.3.3
-------------------------

- Renamed column "GR" to "GRvalue" for GR value table to match other code.
- Fixed erroneous error message in division rate GR value calculation

CHANGES IN VERSION 1.3.2
-------------------------

- Renamed some curve parameters for the relative cell count curve
  - changed "IC" to "rel_cell".
- Changed GRdrawDRC function parameter option for dose response curves based 
  on relative cell counts from 'metric = "IC"' to 'metric = "rel_cell"'.
- Changed GRinf (and Einf) value to the minimum of the mean GR values
  (relative cell count) at the two highest concentrations tested for the 
  case of horizontal line fits (same as GRmax).
- Changed GRmax (and Emax) so that in the case of averaging over multiple 
  conditions, the value taken is the minimum of the mean of GR values
  (relative cell count) at the two highest concentrations instead of the 
  absolute minimum GR value at these concentrations.
- "duration" column in input changed to "treatment_duration" to match the 
  nomenclature in other code.
- Added calculation of GR values from division rates for Case "C"

CHANGES IN VERSION 1.3.1
-------------------------

- Added calculation of GR values from division rates for Case "A"
  - now accepts columns "duration" and "division_time" instead of 
    "cell_count__time0"
- Added a few parameters to calculation
  - "control_cell_doublings" is the number of cell doublings that occur 
    in the control population over the assay, calculated either from 
    initial and final cell counts or given division rate and time of assay.
  - "concentration_points" is the number of different concentrations used 
    in an experiment
